Develop Reference

Why does Visual Studio 2022 suddenly stop showing errors?

As stated in the headline, Visual Studio 2022 suddenly stopped showing errors (and also I can't find public method and variables but that's another question).
I am working in Unity and suddenly it just don't want to cooperate anymore.
I tried closing the application and unity all together and restarted my computer, and nothing worked.

At the top of your screenshot you can see "Miscellaneous Files". This means that the file is not considered to be part of any project.
To see errors and IntelliSense, VS requires source files to exist within a project so that it knows:
What references exist (packages, assemblies, target framework)
What version of the language is being used
Various properties that influence analysis/analyzers
So for some reason your file is not considered part of a project. We can't see your Solution Explorer, so it's not clear why that might be. Most likely you've opened the file via "File | Open". Make sure you create the file within a project, or add it to a project.

One of the endless joys of working with Visual Studio are random inexplicable times it stops working the way it should. Usually these steps work:
Close VS completely
Ensure all bin and obj directories of all projects are cleared
In the same directory as your solution should be a hidden .vs directory. Delete this.
Reopen VS and your solution. You should be back to a normal state within a few moments. Sometimes a "Rebuild All" can accelerate its return to normality too.

Visual Studio 2013 C# Interactive Window

Is there C# interactive window for VS 2013, or any other similar way, without installing VS 2012.
I tried C# Repel, C# Snippet Compiler and Mono Command Prompt, but, all of them don't provide the features of C# interactive window packed with Roslyn for VS 2012.

UPDATE: Found a total better alternative!!! Try CShell, it is free and open source! "A simple, yet powerful, C# scripting IDE" as they promote it.
Check my tweet which was also favorited by Scott Hanselman :)
My old recommendation was: LINQPad

Best way is to install VS 2012 and use C# interactive window provided with its Roslyn. While doing that, wait Microsoft to release C# interactive to VS 2013.

This is taken from one of the links above:
http://social.msdn.microsoft.com/forums/vstudio/en-US/0da45fe7-fbe2-4074-b52f-dc8d7c4b2ba3/c-interactive-in-vs-2013
It worked for me, so hopefully this will help the next person :)
Hi SpencerGR,
I just got upgraded to VS 2013 and wanted C# Interactive, and this is
the first hit when I searched for it, so I figured I would place my
answer here...
Didn't make sense to me that the extension from VS 2012 wouldn't work;
so I hunted down the Roslyn keys in my registry for VS 2012 and was
able to kinda figure out what was going on. After a bit of futzing
around, I finally got it working, so here's the instructions for
whoever might care to try [be warned, I'm sure this isn't supported by
MS, I take no responsibility if something happens to mess up your
computer, and so forth ;)].
Basically it was a matter of
copying some registry keys with slight modification copying some files
and this one is annoying but oh, well] there's a file you have to
change the datestamp on (I did it by opening the file in Notepad++ and
saving it out.) If you don't already have VS 2012 or you don't have
the Roslyn CTP installed you'll need to get the files somehow, and I'm
not sure if there are other registry settings needed or not, but I
imagine if you just manage to get the files out of the CTP distro it
would be enough... No guarantees of course.
Not-Instructions-Just-An-Explanation-Of-What-I-Did-I-Am-A-Trained-Professional-...-Or-Something
;)
copying some registry keys with slight modification; I replaced '11.0' with '12.0' in the keys and values, you might need to change
the paths too if you didn't install Visual Studio in it's default
location. (also posted to pastebin.com/XeP5ai8F )
Save this as a .reg file and open it to import the new keys easily:
Windows Registry Editor Version 5.00.
[HKEY_CURRENT_USER\Software\Microsoft\VisualStudio\12.0\InteractiveWindows\0] "ContentType"="Roslyn C#"
[HKEY_CURRENT_USER\Software\Microsoft\VisualStudio\12.0_Config\InstalledProducts\Roslyn] ""="Microsoft Roslyn CTP" "ProductDetails"="Microsoft Roslyn CTP"
[HKEY_CURRENT_USER\Software\Microsoft\VisualStudio\12.0_Config\Packages\{c5edd1ee-c43b-4360-9ce4-6b993ca12897}] "Class"="Roslyn.VisualStudio.CSharp.Repl.CSharpReplPackage" "CodeBase"="C:\\Program Files (x86)\\Microsoft Visual Studio
12.0\\Common7\\IDE\\Extensions\\Microsoft\\Roslyn C# Interactive Window\\1.2.20906.1\\Roslyn.VisualStudio.CSharp.Repl.dll"
[HKEY_CURRENT_USER\Software\Microsoft\VisualStudio\12.0_Config\Packages\{f5199a4e-6a60-4f79-82e9-fc92a41c4610}] "Class"="Roslyn.VisualStudio.InteractiveWindow.InteractiveWindowPackage" "CodeBase"="C:\\Program Files (x86)\\Microsoft Visual Studio
12.0\\Common7\\IDE\\Extensions\\Microsoft\\Roslyn Components\\1.2.20906.1\\Roslyn.VisualStudio.InteractiveWindow.dll"
[HKEY_CURRENT_USER\Software\Microsoft\VisualStudio\12.0_Config\ToolWindows\{2d0a56aa-9527-4b78-b6e6-ebe6e05da749}] "Name"="Roslyn.VisualStudio.InteractiveWindow.VsInteractiveWindow"
copying some files; basically just need to copy the files mentioned above to the locations mentioned above; I just copied the
'Common7\IDE\Extensions\Microsoft\Roslyn C# Interactive Window' and
'Common7\IDE\Extensions\Microsoft\Roslyn Components' folders from my
11.0 install to my 12.0 install. easy peasy.
and yeah... there's a file in the aforementioned 'Common7\IDE\Extensions' directory called
'extensions.configurationchanged'; I couldn't get things to take, then
I noticed that file. so, as mentioned, I just opened in Notepad++ and
saved back out; I think I had to make a change to the file, so I added
a space. kinda felt kludgy, but I guess it beats VS taking longer to
load due to having to scan the Extensions every time you open it up.
So, that's it! Worked for me, I hope someone else may find this
useful, as it probably took longer to post this than it did to
actually get it working in the first place. ;) It's possible I missed
a step in here somewhere, since I had made a few other attempts before
I found the 'changed' file, so I could have possibly twiddled another
bit somewhere that was necessary that I don't remember. Should be a
good start tho.
I haven't tested it out fully by any means but it shows up in the
'View > Other Windows' list, it opens up just find, and it looks like
Intellisense is working too. Good luck and great code to all! :)
--- Chelle L.

You could also use LinqPad. You can use it to test C# code. It has built in support for loading DLLs and Nuget Packages. Its what I use personally and I love it.
It has a free version, but the paid version has intellisense and debugger

C# interactive finally arrived to VS 2015... You may need to install vs2015.1 to get it..
http://blogs.msdn.com/b/visualstudio/archive/2015/10/08/visual-studio-2015-update-1-ctp.aspx
Good luck... and happy interactive coding!

IWIH describes how to install it and which prerequisites you need.
Let me give you some
Additional information:
After you have installed VS 2015 and its updates (update 3 KB3165756 patch has just arrived) you can bring C# interactive to your screen as follows:
Either via the menu
View -> Other Windows -> C# Interactive
Or press Ctrl + Q and type into the quick launch box:
C# interactive
which allows you to click on View -> Other Windows -> C# Interactive with the mouse.
Afterwards, you have the C# Interactive beneath the error list. Here is an example how you can use it:
Quickstart:
To get help in this window, type #help and press enter.
To execute a statement, simply press ENTER. To type in multiple lines, press SHIFT+ENTER for each line, and for the last line press ENTER to execute the entire statement.
To print the values of a variable, type its name and press enter (in the screen shot, I have done this for variable q)

Datatips (mouse hover over variables in debug mode) not working in Visual Studio 2012 / Win 7 64bit

When I hover my mouse over a variable when debugging a C# app in Visual Studio nothing popups. I expect to see the value of the variable (aka datatips). I'm running Visual Studio 2012 Ultimate (trial edition) on Windows 7 64bit. Does anyone know what may prevent them from showing?
Things I've tried to no avail:
- Reinstall VS
- Search for an enable/disable setting but there doesn't seem to be one
I can see the datatips correctly with the same C# project on Windows 8/64bit with the same version of Visual Studio.

THis helped me: you need to open in VS Tools | Options | Debugger | General and enable the flag [Use Managed Compatibility Mode].

Before running the application check you are running it in Debug mode. If set to Release mode change it to Debug and then run. The debugger will then provide the data-tips.

I have found this solutions:
reinstall Visual Studio as advised here, but you have already tried it
Open your VS->Tools->Import and Export Settings Wizard->Reset all settings->No, just reset settings, overwriting my current settings-> Choose a Default Collection of Settings from MSDN Forum: Debugging - hover watch has stopped working
maybe you have Release build configuration
set Code Optimization property to Disabled under Project property windows
as advised in similar question on SO

I had this problem so I deleted all the *.suo and *.user files I could find in the solution directory and that seemed to fix it.

I had this same problem. My project had somehow gone into Release mode, so I changed it back to Debug mode via Build|Configuration Manager and it was working again, the datatips reappeared.

I realize this is an older post. But I have the exact problem in Visual Studio 2019. The funny thing is that datatips are not showing on my external screens. But if I drag Visual Studio to my laptop screen, it shows without problems. Dragging it back to one of the two external screens and it won't show.
I also have a problem that the Project Properties and Team/Source Control Explorer does not show anything but white content until I switch to another tab and then back. Then it loads. I have tried enabling GPU support in Windows, but nothing.
Has anyone had the same experience?
I will of course try all of the suggestions for the datatips thing, as that's really decreasing my effectivity.

The same happened to me but only with C#, active mode administered compatibility (Managed Compatibility Mode) and it worked well, then I wanted to modify the code while had debugged and came out a motioning message
compatibility mode administered is not supports edit and continue
Then turn it off again, under native support is (Use the legacy C# and VB expression evaluators) enable this option and you can see the value of objects and edit code debugging.

Try deleting the .vs directory and restarting visual studio.

This 3 combinations solved it for me.
- Make sure you are in Debug mode
- Uncheck/Disable Use the legacy C#,VB.NET evaluator (Tools->Options->Debugger)
- Make sure Enable Just My Code is checked.

Using remote debugging on another machine makes it more challenging.
This thread talks about RPC Server being unavailable when using "Use Managed Compatibility Mode", which makes remote debug impossible with Managed Compatibility Mode
Remote Debugging not working. "Unable to attach to process. The RPC server is not available."
Native compatibility had the same effect.
It was only "Use legacy C# and VB expression evaluators" that allowed hover over variables AND remote debugging in my case.

I deleted the project and re-cloned it from git, then it worked. None of the other solutions worked for me.

I ended up with resetting VS Settings to make this work:

Ok, I'm not exactly sure why my Visual Studio 2019 v16.8.2 was not showing the data tips popup whenever I hover over the variables when I'm debugging. FYI, I am using a project that was created on another machine with the same version of Visual Studio. I got it fixed by doing the following steps.
Load up the project and set it to release build.
Visit Tools -> Options -> Use Managed Compatibility Code, set it to enabled. Close the Options menu.
Remove any breakpoints in your code.
Run the project in Release build mode, instead of Debug mode.
Let the program run for 5 seconds and then click red square that STOPS the debugging running program.
Open up the Options again and change the 'Use Managed Compatibility Code' back to disabled(uncheck it). Close Options.
Add some breakpoints and set the run mode back to 'Debug' mode and click Play to debug the program as per normal usage.
Doing these steps in this order solved the problem for me. I'm not exactly sure which steps solve the problem but somehow in doing the preceding list of things, it's now fixed. A reinstall of VS 2019 didn't help.
UPDATE: After going back to my project and attempting to debug, it appears it's back to not working again. I tried the above steps and that only fixes the problem for the first iteration of the loop I'm working in. It appears when the code is working, then the next iteration through the loop and when it comes to my breakpoints, they are no longer showing the little popup window that allows you to inspect the variable data. So doing the above-mentioned steps only solves the problem for the first time the breakpoints are hit.
P.S. I'm using two instances of Visual Studio 2019 and am recreating one of my older apps so that it is up to date. I'm not sure if this has anything to do with the datatip's not showing up when mouse hovers over the variables or not.

I updated the package of RestSharp, and my problem solved. Packages with warning icon on it can cause this problem.

drop this into .csproj of your project (first propertygroup).
<DebugEngines>{351668CC-8477-4fbf-BFE3-5F1006E4DB1F}</DebugEngines>
It's basically as adding for your project manually that it uses compatibility managed mode, since in vs2022 this option does not exist in options.

For me, this worked on Microsoft Visual Studio Community 2017, Version 15.9.9:
If you are facing this issue simply uninstall the current version and reinstall VS. After installing and running debugging mode first time, please choose "Disable Just My code and Continue" selection,it should work.(as shown in the attached screen shot).
If you do not want to uninstall and then re-install visual studio,then try these settings on the existing VS installation:
Go to: Options => Import and Export Settings ==>Reset All Settings==>No Just reset settings,overwrite my current settings =>Finish
after this simply start debugging and choose "Disable Just My code and Continue" option.
3.If you are still having problem,please also make sure by going to project =>properties ==> Configurations that you have configurations set to debug(sometimes configurations are set to release)
Go to Tools=>options =>Debugging ==> General ==> select Suppress JIT optimization on module load

Error Creating Debug Information - Code Won't Compile

I'm using VS 2008. When ever I make a change in my code and try to compile I get the following error:
Error 7 Unexpected error creating
debug information file 'C:\Documents
and Settings\jbezanson\My
Documents\MyProjects\DispatchBoard\DispatchBoard\obj\Debug\DispatchBoard.PDB'
-- 'C:\Documents and Settings\jbezanson\My
Documents\MyProjects\DispatchBoard\DispatchBoard\obj\Debug\DispatchBoard.pdb:
The process cannot access the file
because it is being used by another
process. ' DispatchBoard
Using Process Explorer, it is always devenv.exe that is locking the file. If I run in Release mode this does not happen. It started 2 days ago when I started a WPF application, and since then it happens with every application I work on.
The only info I could find from Google was referring to a bug in VS 2003.
Anyone else have this problem? How do I fix it? It is getting very annoying having to kill the file handle every time I want to compile.

If you have multiple instances of VS open, close other instances (apart from the one you are trying to compile) - this may resolve the issue.

When I have problems with locked files, I use Unlocker. (If you tried everything and it's not working, try this ;)
In case of broken link, here's a mirror.

Have you tried closing VS, deleting obj folder then restarting VS?

I had the same problem this morning and noticed that I had another project open that had a reference to the one that would not compile or debug. I removed the reference (as I didn't actually need it) and it was fine.

I changed the 'StartUp Project' of my solution to a project without reference to the locked file's project.
This solved the issue for me using VS 2010 SP1.
(Process Explorer said msvsmon.exe (started by devenv.exe) locked the pdb file.
After changing the startup project the processes msvsmon.exe and .vshost.exe disappeared and so did the file handle.)
Alex Clark, thank you for pointing me in the right direction.

The only thing that worked for me is to remove the optimizeCompilations="true" attribute from on the compilation element in my Web.Config file.
Compilation time may be a little longer, but it worked well.

To avoid that problem just open the project properties, go to Debug tab an untick "Enable the Visual Studio hosting process"

I had this issue today. In my case, I had just grabbed the data from my company's source control and instantly hit this issue when I tried to compile the project. The issue ended up being that the \bin folder was set to Read Only. To solve the issue, I just made the folder not Read Only.

I just came across the same problem today. And then I realized what went wrong: I had couple of Visual Studio windows opened at the same time, and one of them was in debug mode.
When I stopped debug mode in that one, the problem was solved.
That happens when you have a "fistfull of VS windows" opened.

Right Click The Folder that contains debug .pdb and uncheck the folders read-only propertys then ok. thats it.

This works for me with web projects in Visual Studio Express 2012 for Web:
Press F5 to begin debugging
"Do you want to execute last successful build?" - hit YES
At this point you could try a request - not sure if this step is necessary
Hit the stop button
Recompile successfully

I have solved a similar problem by adding these lines as a pre-build event:
if exist "$(TargetPath).locked" del "$(TargetPath).locked"
if exist "$(TargetPath)" move "$(TargetPath)" "$(TargetPath).locked"
With proper modifications, it might help your problem.

Since you say you have it on all applications you work on it sounds like a more global problem. You could try and reinit the vs2008 by writing
devenv.exe /setup
Edit: link to command line options

This worked for me. What I done was that close my visual studio and delete the .suo file and then re-open the solution. The locking should be disappeared now. Cheers.

Old topic, but something that worked for me. I had 2 projects in my solution, a class library type project and a windows form project. The windows form project was referencing the compiled binary and not the project itself in my case which was causing the lock. After changing the reference to the class library project, it worked properly.

Not need to restart or delete the file.Deleting will not be possible , you will get error message. Just rename the file and that is enough.
VS2010 will create another file for you as it wont find the origional. :)

I had the same issue from time to time. Usually no problem but once in a while... This particular time, it was impossible to work. I would shut the application down, and even that didn't work most of the time. I saw this post and a person said they had no issues until they started a WPF application. I was playing music (radio station) in the background with Windows 8 "Music" app. I had the idea that it was a Microsoft App built with Visual Studio. Once I stopped playing music, I never encountered the error. If you are reading this, see if you have any Microsoft apps running.

I also had the same issue. Tried all the suggestions above with no luck. I eventually change the Build Configuration from Debug to Release, the solution built...

This problem started occurring for me after changing from Cassini to IIS Express as my platform for debugging.
Cassini was much better than IIS Express but doesn't properly support the Integrated pipeline. IIS Express is hopeless.
This seems to be some sort of race condition in Visual Studio or IIS Express. It is nothing to do with one project locking another project - the locks are coming solely from the activity of the web application's build process.
Anyways, none of the above solutions worked for me. Unlocker doesn't seem to be supported for Windows 8 anymore. So instead I tried LockHunter. What I do is keep the LockHunter app open all day. If I get a complaint about some file being locked I copy and paste the file path into LockHunter then try again. This usually sorts out the problem but sometimes takes a few attempts.

Visual Studio 2008 crashes when opening solutions in a TortiseSVN directory? How do I fix this?

I'm using TortiseSVN for my subversion client on a Windows Server 2008 box and I've got a folder with code checked out into it.
When I go to open the solution file that's under source control Visual Studio 2008 starts and before it can even finish loading the solution from what I can tell Visual Studio crashes. I'm trying to open a solution that has VB code in it. It gives no error messages or warnings. It's just gone.
I have checked the files and they all seem fine. The solution file seems fine when I look at it with a text editor.
This is also Visual Studio 2008 SP1 and I've got all the latest .NET service packs installed.
Has anyone else seen this before and know how to fix it?
Edit: I just did an SVN export to a new directory and it still crashes in the exported directory where there is no longer any SVN attached to it.
Additionally, it crashes EVERY time I try to open the project that came from SVN.

You should be looking at the solution file with an xml editor, at least then you will get some help for subtile flaw's in the formatting or something like that.
You can also submit feedback to Microsoft on the VIsual Studio Connect site, if the bug turns out to be real.
Some commonsense things todo however would be, goto your visual studio command prompt, start off with "devenv /ResetSettings", that often helps isolate any weirdo add-on or something lke that.
Also, try to build clean with msbuild or vcbuild, then build fully with either one (i.e. if vcbuild can not build your solution, use msbuild). That can help by laying out the symbols and such and maybe clear out some corrupted file or something.
You also may have .suo files from your subversion, those are binary files that do contain some settings, it's common for people to accidentially check them in, but they are usually better off being kept on a per-developer basis (not in the source tree). The /resetsettings will likely clear these out also, but you may want to make sure.
You can also double check the path's to all of the assemblies referenced, that your not going from a 32/64 bit host, and the CLR DLL's are in different path's now etc...
One last thing, if your really stuck, you can get a stack trace and debug the crash a bit ;), see where the fault is occuring and search that module online, your'll often find that somebody may have a specific solution.
Oh yeah, also, hooker's can be trickey. Don't trust them for a minute. Make sure you set tsvn's "only load in windows exlporer" option and configure it specifically for what folders on your system have local-svn working directories, this will greatly reduce the working set for their shell extension. On most any system, over time, one program or another (apple irw.exe or adobe pdf-preloader.exe sort's of ad-ware) will try to work it's way into your shell. You should try to make sure your dev box is rather clean from anything hook's, simular to what VladV was saying...

I had a similar problem and I fixed it and afterwards I wasn't quite sure how I managed it.
It basically involved going to the tools/options menu and setting the source control plugin to none. However, I obviously had to have had the solution open in Visual Studio if doing this was to fix the solution, but yet I thought the problem was I could not open the solution.
The only possible scenario would be if I was able to open the solution, but not open any of the projects inside it, hence able to change the source control settings immediately after opening the solution.
Does that make sense?

Try opening your solution and projects files in a text editor, and looking for anything strange.
I once heard of a similar problem: a solution contained SVN bindings created by AnkhSVN, but Visual Studio had no AnkhSVN installed, and failed to open the solution without giving any meaningful error information.