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I have hundreds of errors saying type or namespace doesn't exist (some are types and some are namespaces). When I click to view the error it initially opens the file and shows the squiggly line under code in question, however within a second or two the squiggly line disappears and so does the error.
After I finish opening up all the files with "errors", all the errors disappear and it compiles fine. However, if I close any the files then the error reappears for that file.
This happened after I tried to merge branches. Not really sure how to proceed to find the root of the issue, or whether there even is a real issue... maybe this is just some bug in Visual Studio and I need to do something to clear some kind of cache to fix the problem?
Please advise.
Update:
I have tried all of tymtam's suggestions but to no avail.
However, after deleting the .vs folder, now the errors don't even go away when I open the files so I can no longer build by doing that either.
I am thinking the error may have something to do with dll versions or something like that but I have tried to rebuild and replace all dlls with latest ones and that hasn't helped either.
The problem for me was an outdated version of the .net framework. The new assemblies I was referencing were 4.8 based but my projects were targetting the 4.6.1 framework. Updating the project files to target 4.8 fixed it.
IntelliSense, which is likely the source of these errors, sometimes takes time to adjust to changes caused by switching branches (or more generally code changes that happen suddenly).
Here are the steps that should help, in order:
(Re)building the solution
Restarting Visual Studio
Closing Visual Studio and deleting .vs folder in the root of the solution folder.
Finally you can see if the errors are 'real' by changing what the Error List window shows to Build Only. I would recommend to have it as 'Build + IntelliSense' normally, and using Build Only only on special occasions.
Focus on the 1st error
More generally, when dealing with a large number of errors it's not a bad idea to look at the first one only, solve it, and build the code. A single syntax error can result in many errors and trying to solve the 2nd and subsequent errors would be futile.
In addition to the above, make sure you also look at the warnings (possibly information messages).
In my case, I had them turned off to focus on the errors only and missed the fact that my two projects were set to different versions of the .NET framework.
I did these two things to fix my problem:
I used WinMerge to copy files from the old branch over everything in the new branch for the application in question.
I updated the framework on the project to the latest version.
Originally, I did those two steps except I used TFS to merge the old branch to the new (instead of using WinMerge to copy/overwrite files) and accepted the old version for all conflicts.
This was the nuclear option as I lost any changes that were made in the new branch :(. I have a copy that I can use WinMerge to try to manually merge changes back in but it's definitely frustrating.
I'm not sure if anyone else has encountered this but often, when I open this particular solution, I see a whole list of errors (see below).
If I double click one of them, then Visual Studio seems to wake up and the errors relating to that particular cs file disappear. This isn't a critical issue and is more on an irritation than anything else but I wonder, is there perhaps something wrong with my code that's causing this false-positive or is it random Visual Studio behaviour?
I had this problem too.
Deleting bin and obj folders not work.
Cleaning solution not work.
Various platform I need to be as is.
Helped me close solution and delete folder .vs, which is often full of problematic mess. After opening solution all false errors disappeared.
As mentioned in a comment, you can do a Clean and Rebuild. If that does not work for you, you can browse to the solution folder and within each of the project folders delete the bin and obj folders. Then perform a build.
You may also want to look into your Configuration Manager and ensure that all of your projects are set to the same Configuration (Debug/Release) and Platform (Any CPU/x86/etc...) and marked to build for that configuration.
Finally, you may also want to check the Build Order for your solution. Ensure that projects are all built in the proper order.
-- Edit:
On thing brought up in comments that I will add here was to make sure that any library projects in the solution are added as Project References rather than referencing the output DLL directly.
Something that has only become evident in later years, and is only relevant upon reflection on this old question, is that the particular solution that we experience this issue in contains a Website project and NOT a WebApplication project. This became evident when we started to look deeper into these recurring errors and noted that they only ever related to codebehind files and all had to do with the Control Name not existing in the current context.
Amongst the various differences between the two project types, it seems that the lack of designer files for each ASP page may be a contributing factor. The error disappears as soon as you double click it potentially indicating that VS is not able to keep track of the control references until you open the relevant page / codebehind file.
We're moving over to a Web Application as a temporary measure.
Hope this insight helps someone else!
I have a solution that includes various C# projects, and I just now noticed that I can't change the default namespace on any of them.
When I go to Properties --> Application on any of the project and change the "Default Namespace" field, a fatal error dialog pops up that says:
exception of type 'system.runtime.interopservices.externalexception' was thrown
At this point Visual Studio becomes unusable, as I can't close it or leave the screen, every click or button combination I press makes the same dialog pop up. The only thing I can do is terminate VS with the task manager.
I got around it by just renaming the <RootNamespace> node in the .csproj file
Maybe you should try to do this in another way:
Ctrl-H - Find: PreviousNameSpaceName Replace: NewNamespaceName
You can also right click the namespace in code and Refactor->Rename.
What is more: you can change the names of your projects, solutions, directories - etc. Namespaces, when adding new files, are generated using these names in fact.
I had to investigate the issue in our company and I found another workaround in our case. So I think it make sense to add it here.
Possible Solution
Check if you have more than one suo-File for the project/solution and delete the one which doesn't has the ".v12.suo" naming (better delete both)
Story behind:
We still have two Visual Studio installed (2010 and 2013) and some of our developer worked recently on 2010. So they had on the file system a regular ".suo"-File. Afterwards (some weeks later) they started to use 2013 (which created a ".v12.suo"-File).
We renamed both suo files, started VS2013 (which created the v12.suo) and were able to rename the namespace without a crash. In addition we had this issue not on all solutions. I didn't see yet a pattern, but in our case it happened mostly on solution with at least two projects and referenced project-libraries.
I have stumbled into an issue that is really annoying.
When I debug my software, everything runs OK, but if I hit a breakpoint and edit the code, when I try to continue running I get an error:
Metadata file 'XYZ' could not be found
After looking around for a while, I found some a similar issues, but they were all regarding a build failure, which is not my case (this happens only after edit-continue).
What I have tried so far:
My code is compiling and running.
I cleaned the solution and restarted VS.
I made sure that the missing file's project is being build for the configuration I am running (in configuration manager).
I manually built the missing file's project.
Some extra info:
It does not matter what I change, still get the same error (the change is not related to the missing file).
This happens also when I pause and continue (not only breakpoints)
I am running the project using a custom configuration (configuration manager...). When I run it using the default Debug configuration the error does not occur.
Any ideas?
Eventually what solved the issue was:
Clean every project individually (Right click> Clean).
Rebuild every project individually (Right click> Rebuild).
Rebuild the startup project.
I guess for some reason, just cleaning the solution had a different effect than specifically cleaning every project individually.
Edit:
As per #maplemale comment, It seems that sometimes removing and re-adding each reference is also required.
Update 2019:
This question got a lot of traffic in the past, but it seems that since VS 2017 was released, it got much less attention.
So another suggestion would be - Update to a newer version of VS (>= 2017) and among other new features this issue will also be solved
As far as I can tell, this happens when the project dependencies gets messed up for whatever reason (whilst all the inter-project references are still intact). For many cases, it is NOT a code issue. And for those who have more than a few projects, going through them one at a time is NOT acceptable.
It's easy to reset project dependencies -
Select all projects and right click unload
Select all projects and right click reload
Rebuild solution
For those who have an issue in their code or some other issue that's causing this problem you'll obviously have to solve that issue first.
One possible reason could be you have upgraded the some of your projects (in the solution) to higher version e.g. from .NET 4.0 to 4.5 This happened in my case when I opened the solution in VS 2013 (originally created using VS 2010 and .NET 4.0). When I opened in VS 2013 my C++ project got updated to .NET 4.5 and I started to see the problem.
Generally this kind of error comes with human mistakes like if we change the namespace in some improper way, or changing folder names from explorer for current project etc, where compiler is unable to detect sometimes.
I came across the same error, to resolve which I tried few steps. Please follow all the steps :
Clean whole Solution
Right Click on every Project in your solution , Go to Properties and make your Default namespace as well as Default assembly name same as in your code (i.e namespace before class name)
Check Folder names for each project by going through the explorer(Where your project solution is). If not matching with your project names, make it similar (Like step 2) to them.
Remove all your references from each project relevant to another of same solution, and add it again.
In Your Project Solution folder, you will find Visual c# Project file. Right click and open with Notepad. In your initial lines you would find for lines for every project like below:
Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "**Client**", "**Client** \ **Client**.csproj", "{4503E259-0E3B-414A-9074-F251684322A5}"
EndProject
Check again Foldernames (I have highlighted in BOLD) and make it similar to what you did in step 2.
Clean the whole solution again
Build The Solution (If doesn't work try building individual after cleaning again)
Make sure all your dependent projects are using the same .Net Framework version. I had the same issue caused by a dependent project using 4.5.1, while all others were using 4.5. Changing the project from 4.5.1 to 4.5 and rebuilding my solution fixed this issue for me.
XYZ couldn't be found because is not built yet....
Right click on the solution and check Project Dependencies, the Project Build Order should also change according to the dependencies that have been set.
The only thing that worked for me was to delete the Solution User Options (.suo) file. Note that, this is a hidden file.
To locate this file, close your Virsual studio and search for .suo from the file explorer within your project.
PS: a new .suo file will be created again when you rebuild your project and hopefully this newly created one wont give you issues.
I hope that helps someone get rid of this anoying error :).
I had this problem for days! I tried all the stuff above, but the problem kept coming back. When this message is shown it can have the meaning of "one or more projects in your solution did not compile cleanly" thus the metadata for the file was never written. But in my case, I didn't see any of the other compiler errors!!! I kept working at trying to compile each solution manually, and only after getting VS2012 to actually reveal some compiler errors I hadn't seen previously, this problem vanished.
I fooled around with build orders, no build orders, referencing debug dlls (which were manually compiled)... NOTHING seemed to work, until I found these errors which did not show up when compiling the entire solution!!!!
Sometimes, it seems, when compiling, that the compiler will exit on some errors... I've seen this in the past where after fixing issues, subsequent compiles show NEW errors. I don't know why it happens and it's somewhat rare for me to have these issues. However, when you do have them like this, it's a real pain in trying to find out what's going on. Good Luck!
Well, my answer is not just the summary of all the solutions, but it offers more than that.
Section (1):
In general solutions:
I had 4 errors of this kind (‘metadata file could not be found’) along with 1 error saying 'Source File Could Not Be Opened (‘Unspecified error ‘)'.
I tried to get rid of ‘metadata file could not be found’ error. For that, I read many posts, blogs etc and found these solutions may be effective (summarizing them over here):
Restart VS and try building again.
Go to 'Solution Explorer'. Right click on Solution. Go to Properties. Go to 'Configuration Manager'. Check if the checkboxes under 'Build' are checked or not. If any or all of them are unchecked, then check them and try building again.
If the above solution(s) do not work, then follow sequence mentioned in step 2 above, and even if all the checkboxes are checked, uncheck them, check again and try to build again.
Build Order and Project Dependencies:
Go to 'Solution Explorer'. Right click on Solution. Go to 'Project Dependencies...'. You will see 2 tabs: 'Dependencies' and 'Build Order'. This build order is the one in which solution builds. Check the project dependencies and the build order to verify if some project (say 'project1') which is dependent on other (say 'project2') is trying to build before that one (project2). This might be the cause for the error.
Check the path of the missing .dll:
Check the path of the missing .dll. If the path contains space or any other invalid path character, remove it and try building again.
If this is the cause, then adjust the build order.
Are you using a database code generation tool like SQLMETAL in your project?
If so, you may be facing a pluralized to unpluralized transition issue.
In my case, I have noted that some old pluralized (*) table names (upon which SQLMETAL adds, by default, an "s" letter at the end) table references to classes generated by SQLMETAL.
Since, I have recently disabled Pluralization of names, after regerating some database related classes, some of them lost their "s" prefix. Therefore, all references to affected table classes became invalid. For this reason, I have several compilation errors like the following:
'xxxx' does not contain a definition for 'TableNames' and no extension method 'TableNames' accepting a first argument of type 'yyyy' could be found (are you missing a using directive or an assembly reference?)
As you know, I takes only on error to prevent an assembly from compiling. And that is the missing assemply is linkable to dependent assemblies, causing the original "Metadata file 'XYZ' could not be found"
After fixing affected class tables references manually to their current names (unpluralized), I was finnaly able to get my project back to life!
(*) If option Visual Studio > Tools menu > Options > Database Tools > O/R Designer > Pluralization of names is enabled, some SQLMETALl code generator will add an "s" letter at the end of some generated table classes, although table has no "s" suffix on target database. For further information, please refer to http://msdn.microsoft.com/en-us/library/bb386987(v=vs.110).aspx
Hope it helps!
I had this error come up. I followed all of the solutions here but nothing worked. I was using Visual Studio 2013 Professional. I couldn't get the individual project rebuilds to work and I finally figured out there was a circular dependency in my references. Visual Studio does a pretty good job normally of warning you if you are adding a reference to something that references back, but for some reason it didn't in this instance. I added a reference to a project that referenced the project I was working on - and it accepted it. VS bug perhaps?
My 5 cents.
This problem started after a solution wide clean.
I managed to get the problem to go away by setting the Active Solution configuration in: Build -> Configuration manager to release. Then build and set it back to debug again. The build succeeded after that.
Close VS, locate and remove the 'packages' folder from outside of visual studio. Restart VS and build -> all dependencies are reinstalled
Visual Studio 2019 Community 16.3.10
I had similar issue with Release build. Debug build was compiling without any issues.
Turns out that the problem was caused by OneDrive. Most likely one could experience similar issues with any backed-up drive or cloud service.
I cleaned everything as per Avi Turner's great answer.
In addition, I manually deleted the \obj\Release -folder from my OneDrive folder and also logged to OneDrive with a browser and deleted the folder there also to prevent OneDrive from loading the cloud version back when compiling.
After that rebuilt and everything worked as should.
this happens because of the difference of names in the folder name and namespace name. If u create a namespace in a certain name , and later you rename it the namespace will have the old name itself. And the compilation will take the old path to find the .dll and .exe file . To avoid this open the .csproj file of each namespace with a text file , and find the old path in the file.
remove this, clean and rebuild the solution. This worked for me. I spent an entire day working on this problem.
I had this and managed to fix it using this SO answer:
Metadata file '.dll' could not be found
I had to uncheck all of the boxes, click Apply, reenable all of the checkboxes and then click apply again, but it fixed the problem.
I just ran into this issue and after an hour of screwing around realized I had added an aspx file to my product that had the same name as one of my Linq-To-Sql classes.
Class and Page where "Queue".
Changed the page to QueueMgr.aspx and everything built just fine.
For a new build, it could be that some dependencies aren't installed. For me it was Crystal Reports.
It happens when one project dll is failing and that is referenced by number of projects. So first fix it and then Build individuals.
I ve had this problem and it has started after importing our solution to TFS as a new project.I came across this topic and found a quick solution with some inspiration from your answers.
All i needed to do is to rebuild the project thats supposedly lost its metadata file and voila , problem solved.
There's also one another silly reason which you should check with patience... as it occurred to me after wasting 4hours searching for answers:
The story to me was that I accidentally changed a small line of code among thousands of c# class files and then trying to rebuild the solution. As you could imagine, I ended up with 40+ meta data file missing errors and with 1 compilation error among them -- which I didn't check carefully, purely thinking all errors were the same!
after 4 hours searching and then accidentally double checking my error list, I found that silly code error, fixed it, compiled, and then error disappeared.
Not a good answer to your problem, but do hope my case wasn't same to yours.
I had the same problem. In my case I had by mistake I had set all the projects apart from the project with the main method as console application.
To resolve I went to every project other than the one with main function and right click> properites > output type > class library
it was happened to me because I've a strange clash in the namespaces:
I had
AssemblyA
with namespace
AssemblyA.ParentNamespace
witch defines ClassA
and in the same assembly another namespace with name
AssemblyA.ParentNamespace.ChildNamespace
witch defines a different ClassA (but with the same name)
I had then in AssemblyA.ParentNamespace IInterfaceB witch had a method that in the beginning returns IEnumerable and a ClassB witch implements IInterfaceB
I had later modified the method in ClassB to return IEnumerable but I've forgot to update the IInterfaceB definition, so the method there was still returning IEnumerable
the fun fact was that the solution still complile if I did a rebuild all, but the tests witch refers AssemblyA didsn't work and returns the "Metadata file could not be found"error.
updating InterfaceB to correctly return IEnumerable as its implementor ClassB did solved the problem, unfortunately the error message was vague and also the fact that the compilation worked makes me suppose that maybe there is something to fix in the compiler
A coworker was running into this problem and the cause was eluding us. Eventually we realized that the project directory (and therefore the path to the NuGet packages) contained %20 (thanks, some Git gui tool which shall not be named) and the error messages showed that the compiler was looking for an very similar-looking path but one which had to %20, rather a space. Apparently something in the build system somewhere performs HTML-decoding on local filesystem paths.
Renamed the working copy directory and everything started working.
I had this issue too.
It started after I did a little folder tidying in my project.
I then tried to compile and got many duplicate class errors. (despite them not being duplicated. I think the linking was just out of wack)
Upon checking these, the errors would all disappear leaving only the "Metadata file ...debug\application.exe could not be found" error.
I solved this by looking in the build output window to find which classes were duplicated.
I would then right click the class name and "go to definition".
there will be two definitions to select from, open them both, the second definition will seem to open the same file again, however the second one will identify as the error source(red underline).
Delete all the code out of the file and save(This will not effect your actual file).
This should now compile correctly.
Ensure that there are no spaces in the path to your project...
I am using Windows 10 with Visual Studio Community 2019 and I was cloning a multi project solution as it was from a GIT repo. I was having this error with all other dependencies in the solution along with a E_POINTER error. Its path, inherited from GIT, had spaces like C:/repos/MY PROJECT NAME/ ...
I deleted it, cloned it again and make sure that its path contained no spaces like C:/repos/MY_PROJECT_NAME/ ...
That fixed my problem.
I had same issue too.
In my case, I recently add an internal class to somewhere in project. One of the dependencies in solution has same class name and both of them are added correctly to references.
I changed my last activity and rebuild, it works.
Be sure that your compiler messages are valid. In my case I catch reference error from there, not listed as an error in Error List.
Why does Rebuild fail with no errors?
Since this morning, this error keeps showing up. I build the entire solution (25 C# managed projects) and a "Rebuild All failed" appears, but without any errors! (I have 13 warnings about COM not supporting Generics, but it's "normal" because one dll is exposed as COM.)
Not an answer per se - but you're better off looking at the output window and seeing what it says there.
Also, to help with that you might want to look at your MSBuild verbosity - as shown on this screenshot (last two options):
Beware - the highest level generates a MASSIVE amount of information.
Finally - running msbuild from the solution folder in a command prompt will really nail the issue - because error messages and warnings come up in red and yellow respectively.
I found my own solution and it is simple:
When this error occurs, save the project and close VS 2013. After that, re-open VS2013 and open the last project.
It works like a charm. But it is very annoying every time!
Many people reported this problem in VS2010, VS2012 and VS2013.
Could be a corrupt Solution User Options file.
Close the solution, delete its .suo (.v12.suo for VS2012+), reopen the solution, and Visual Studio will build a new one. You will lose the StartUp Project, breakpoints, bookmarks, which files are open, which projects/folders are expanded, etc. But that's all minor compared to the solution not building!
I had the same problem. I was trying to refrence a higher .net framework version(4.5.2) to lower .net framework version(4.5) which was causing build error. I made the version same in both projects and it worked.
Check the Output Window (View -> Output) as that will tell you what's going wrong. Sometimes a reference might be missing or there is an issue with the targeted version of .NET for one project in a solution.
Have you tried to clean the solution befor rebiuld it?
This is the list of checks & things I would do if I were you (try to build after each step):
Is error list activated? (Sometimes I forgot to activate and I can see only warnings & messages)
Check output window for error messages..
Clean solution.
Double check after clean that everything is deleted from debug folders.
Build it in release mode.
Build solution project to project until you isolate problematic project.
Remove COM and comment code to see if is this the source of problem.
Restart VS2010.
Restart windows.
Few moments ago I fix it with repair of .NET Framework installation (.NET Framework v4.0 Extended in my case).
I had the same issue in VS 2015. I tried the following with no success:
Close VS project and reopen
Close all open VS projects and reopen just the project that had the issue
Clean solution
Rebuild solution
Delete all files in bin\debug and bin\release
Lastly I tried Keith Robertson's answer, delete .suo (\Visual Studio 2015\Projects\[ProjectName]\.vs\[ProjectName]\v14\.suo). Although this didn't get me a good build, it did finally give me an error message stating that I had two entry points to my application. I went to application properties (Alt + Enter) and select a Startup object from the drop down.
This error seems a bit generic to me. I also went through this situation, but I managed to solve it differently than any of the ones mentioned here.
I have a project and several dependencies. And one of these dependencies has undergone a change.
When compiling the main project in debug mode, I verified that everything was ok.
However, switching to release mode and recompiling the problem occurred.Rebuild all failed and 0 Errors
By analyzing the debug output, I encountered an error:
Although the build dependencies are configured correctly. When compiling in release mode, the main project did not find the new method created in the secondary project.
So I had to recompile each secondary project one by one in release mode. After that, I recompiled the main project and everything worked.
Hope it helps someone!
I just had the same thing. For me, it helped to restart VS and run it as Administrator.
Select the appropriate target framework
- Right click on project
- Properties
- In application tab, Select the target framework
clean the solution
Try and build each project and see where the issue is.
Check each of the references (of each project) to make sure not have the yellow warning sign
Has the solution ever built?
I just had this happen to me, and realized that I left a '#error' line in my code and forgot about it. When I tried to build, the build failed but the #error line didn't show up in my errors.
Try searching all for '#error'
I fixed it on my new implementation of Visual Studio 2013 by going to the database project / Project Settings and noticing that the Target Platform was SQL Server 2014 instead of 2012 like it should be.
Once chance of getting this error is when we try re naming the service reference name, we give some other name in the service reference, but in the namespace some where it will be referring the old name, so if you delete and add a service reference then keep the same name, else we may face this error, but we can see the error in the Output window.
There are apparently many causes of this. I just found the cause of my issue: the .NET version of a new project I created was higher than the version of the top-level project. (4.5.2 vs 4.0)
I got a similar issue today, and fixed it with repair.
Start
Run…
Appwiz.cpl
(Find your installed Visual Studio version)
Right click
Change
Repair
In my case it was the wrong date and time of computer.
I was getting no feedback/messages/errors. Just that all projects failed to build.
I closed and tried again--I noticed an error saying "you are not authorized to access..."
I clicked on my account, re-entered my credentials, and rebuilt the solution.
Voila! I got what I am used to seeing when I build a solution -- plenty of errors in all their glory.
Hope this helps someone.
Here's yet another reason which may sound familiar to some. I had integrated some code into my solution that wrapped a DLL. The C# code file that came with it offered a nice managed API and handled the low-level LoadLibrary stuff to access the DLL. Both had the same base name, so I had SomeName.cs and SomeName.dll. I could just drop it into any project and it would work.
This wasn't so nice after a while as I started using it in different projects. I got copies of both the DLL and the wrapper code in multiple projects. So I figured it would be better to drop the wrapper code and the DLL into a new class library project and then reference that new project from other projects.
After I had done that, I started to get this issue. The build went well up until the very last stage and then failed without error. Output showed nothing but successes.
The problem was the name of the wrapping class library project. I used the same base name (SomeName) for this. By default the assembly name would be SomeName.dll and I already had one such file (the DLL to be wrapped), thus I had a conflict with output files.
After renaming the wrapping project and its output assembly to SomeNameWrapper, the problem went away.
This may not be your exact cause but it seems likely you have some name clash or deployment issue as well. And it is not surprising the compiler won't give you an error because there is no problem in the compilation phase, the trouble starts with deployment and apparently this does not come out in an obvious way.
I had the same problem the original poster was displaying with 0 errors and Rebuild all succeeded. The Output tab showed a message that a referenced dll was built with a higher version of the .NET Framework.
Changing the .NET framework to match resolved the issue I was having with 0 Errors and Rebuild All succeeded.
The solution:
Because Prerequisites not set for debug set only for release
01-Change solution configuration ( in main screen )
set (debug to release)
set solution platform to (Any CPU)
02-Set Prerequisites for debug ( If you want to continue in debug mode )
03-set target platform version for all Projects
Some of the files included in your solution are not in the correct directories, or you have changed the name of one or more directories in your application. In the solution explorer under Setup review the list of all files and remove those that are not properly listed in the SourcePath Property.
One of my dependency in View file caused this. Check your view files for any dependencies which is not injected yet.