Sitecore 500 Error Logging / Alerts - c#

Problem
Currently, I'm looking to serve a custom 500 error page as well as log and alert a web master about the condition that was hit (What URL, stack trace, timestamp, etc.).
I tried defined custom http errors under system configuration, but the error pages were not hit.
I am able to handle 404s and their related errors (layoutnotfound).
Question
Should I intercept the context in global.asax to handle the 500 errors and return a custom page? Is there another way with Sitecore to achieve what I'm looking for?
Mainly, I'm looking for best practice of logging / alerts for 500 errors with Sitecore

Try using ELMAH.
Here is an article on using it with Sitecore.

Elmah is great and does a good job. You can also use log4net to log exceptions. All you do is add an application_error method in global.asax and you can track all the errors that occur. You can also add different appenders and can log messages in a log file, database and email them.
Here is the code that logs the error and includes some additional information like url and Current sitecore item:
private static readonly ILog log = LogManager.GetLogger(typeof(Global));
protected void Application_Error(object sender, EventArgs e)
{
if (Context != null)
{
Exception error = Context.Server.GetLastError().GetBaseException();
log.Fatal(
GetErrorMessage(), error);
}
}
private string GetErrorMessage()
{
StringBuilder sb = new StringBuilder();
sb.AppendLine("Application_Error: Unhandled exception has been occured.");
try
{
sb.AppendLine("Current Request: " + Context.Request.RawUrl);
Sitecore.Data.Items.Item currentItem = Sitecore.Context.Item;
if (currentItem != null)
sb.AppendLine(String.Format("Current Item ({0}): {1}", currentItem.ID, currentItem.Paths.FullPath));
if (Sitecore.Context.Database != null)
sb.AppendLine("Current Database: " + Sitecore.Context.Database.Name);
}
catch { } // in no way should we prevent the site from logging the error
return sb.ToString();
}
If you want an easy solution I would recommend going with Elmah. If you want to have more control and more logging options you should go with a custom log4net solution.

I tried defined custom http errors
under system configuration, but the
error pages were not hit. I am able to
handle 404s and their related errors
(layoutnotfound).
On that particular point...Be aware that custom errors behave differently when accessed locally. Also, by default you need to use physical files (not sitecore pages) for these pages. You need be aware of IIS behaviour when returning status codes over 200 and how it is dependant on the configuration within web.config and (if running in integrated mode) the section. In particular, see the flow chart half way down the first link below.
http://learn.iis.net/page.aspx/267/how-to-use-http-detailed-errors-in-iis-70/
http://www.iis.net/ConfigReference/system.webServer/httpErrors
http://msdn.microsoft.com/en-us/library/ms689487(v=VS.90).aspx
You might also want to change the RequestErrors.UseServerSideRedirect setting to "true" to provide better http responses without redirects.

Related

Change server variable values that are logged in Elmah

I configured Elmah in my application and when I looked at the error logs I saw that in the User section Elmah logged an ID instead of the current logged in username a shown below.
I was wondering if there is a place where I can change how the values of these server variables are set so I can put say an email or proper username in the Auth_User variable..Looking at Elmah documentation I was only able to figure out how to filter out Error logging but not actually how to update server variable values before logging.
I've written a blog post about exactly that: Enrich ELMAH errors using error filtering hook.
To summarize, use ELMAH's error filtering to overwrite the message logged to ELMAH.
In Global.asax.cs add the following code:
void ErrorLog_Filtering(object sender, ExceptionFilterEventArgs args)
{
var httpContext = args.Context as HttpContext;
if (httpContext != null)
{
var error = new Error(args.Exception, httpContext);
error.User = GetUserFromDatabase();
ErrorLog.GetDefault(httpContext).Log(error);
args.Dismiss();
}
}
How you implement the line where you set the User property on error will be up to your application. But the code will let you set something like the user's name, username, or email.

ASP.NET Override all standard http error responses

I have created a custom object that i use to generate a json error response for all error. The issue i am having is there are some errors that i cant catch. For example, if i try to call an action that does not support GET the default response is
{"Message":"The requested resource does not support http method
'GET'."}
This is fine, but i want to control the format. I want to control every single automated error like this so i can make sure that nothing gets output that i dont want to be output. I need to be able to gracefully let the client know if a code exception occurs.
I found this and this seems to be what i am looking for, but it doesnt seem to be catching the errors as there are no matching actions for these . How to override all standard error pages in WebAPI
I tried to implement this, but i still get the same error message from above even when i have this in the main controller.
[AllowAnonymous]
[ActionName("405")]
[HttpGet]
public string Status405()
{
return "error";
}
I was hoping there would be an onerror event or something that would act as a catch all so i could override everything. I tried to work based off the HttpResponseEx
public class ErrorFilter : System.Web.Http.HttpResponseException
{
public override string Message
{
get
{
return "My custom response based on whatever params are in this error";
}
}
}
This doesnt work either and i can see why as it doesnt tap into any events that get triggered.
Surely there is a way to do this. How is it normally done?
In the web.config, you need to turn on custom errors. By default it's set to remote, which allows the developer to see the stack trace and the end user to see a nice error page. You want to set this to on. See here for more details https://msdn.microsoft.com/en-us/library/h0hfz6fc(v=vs.85).aspx

ASP.NET MVC 4 Trigger Error Page

I have been looking for a way to define my own errors in ASP.NET MVC4 using C#. For example, say I have a C# file where I encounter an exception. I would like to trigger the ASP.NET default error page and fill the title and description in with my own error.
To clarify, I am not looking to create a custom error page, as I already know how to do that. Instead, I want to trigger and display my own error message on the default ASP.NET error page. I would like to avoid throwing an exception and never catch it, as I feel that might be a corny way of making ASP.NET choke.
Can anyone show me how I can trigger the error page?
Thank you for your time.
You will get this by adding this into Global.asax file.
protected void Application_Error(object sender, EventArgs e)
{
var httpContext = ((MvcApplication)sender).Context;
var currentRouteData = RouteTable.Routes.GetRouteData(new HttpContextWrapper(httpContext));
}
You will get all the details in "currentRouteData" then you can do whatever you want to do with this errors.

Server.Transfer causing Session exception

In my global I have the following code to handle when an error occurs
//[..] code goes here
Server.Transfer("~/Error.aspx?ErrorID=" + errorId);
It used to be a Response.Redirect which worked perfectly except that it changed the url (which is why I want to use Server.Transfer)
Unfortunately, now when it tries to load the Error page, it crashes on the Masterpage when it tries to refer to the Session
HttpException:
Session state can only be used when enableSessionState is set to true,
either in a configuration file or in the Page directive. Please also
make sure that System.Web.SessionStateModule or a custom session state
module is included in the \\
section in the application configuration.
I do have enableSessionState in both my config and my page.
I also found some links which suggest using Context.RewritePath - that just causes a blank page to load for me.
Using Response.Redirect works perfectly and as expected, so I assume Server.Transfer is the issue here. What is it?
EDIT Code:
protected void Application_Error(object sender, EventArgs e)
{
lock (_lockMe)
{
Exception ex = Server.GetLastError();
if (ex != null)
{
if (ex.InnerException != null)
ex = ex.InnerException;
ErrorLoggingManager.AddError(ex, new MembershipData(), ...); //etc
}
Server.ClearError();
//Some other database code for cleaning up some stuff when an error happens
}
try
{
if (Response != null)
{
//Get the last error logged
MyDataContext db = new MyDataContext();
int errorId = db.LoggedErrors.OrderByDescending(le => le.ErrorId).Select(le => le.ErrorId).FirstOrDefault();
Server.Transfer("~/Error.aspx?ErrorID=" + errorId);
}
}
catch (Exception)
{
}
}
As you have not posted much code. So without seeing the actual implementation you have done. I could suggest you below points.
Point 1. First of all, you need to check if SessionState is enabled for pages. You could set them globally in web.config file. Try the snippet given below in web.config
<configuration>
<system.web>
<pages enableSessionState="true" />
</system.web>
</configuration>
Point 2. And put your Redirection in Application_Error in Global.asax.
public void Application_Error(object sender, EventArgs e)
{
HttpApplication app = (HttpApplication)sender;
app.Server.Transfer("~/Error.aspx?ErrorID=" + errorId,true);
}
Point 3. Also check if your SessionStateis set properly in IIS too.
Details are on MSDN to enable sessionstate
Hope this helps..!!!
From what I understand, Server.Transfer sends the content of another page to the client rather than the requested content. If that is the case, then I am wondering if it does not have something to do with applying a master page to the error page? I had a similar error years ago with earlier technology and it turned out that the master page did not like what I was trying to do.
I hope this helps at least point to a solution.
Here's what the problem is:
If there is a page render exception (ex. "File Not Found") then Server.Transfer screws up the session. This has something to do with it being called during the page render.
As long as you are not appending headers before the error occurs, Response.Redirect will work just fine; if you are, however, using Response.AppendHeader then Response.Redirect will not work during a page render.
Try using HttpContext.Current.RewritePath instead. That should fix all these problems. For whatever reason, RewritePath() does not care that the page hasn't finished rendering.
why not just use customErrors in web.config to do the redirect?
<customErrors mode="Off" defaultRedirect="~/Common/Error.aspx">
<error statusCode="403" redirect="~/SM_AccessDenied.aspx" />
<error statusCode="404" redirect="~/Common/FileNotFound.aspx" />
</customErrors>
I had the same problem in a different context a while ago. I don't know if it is your case, but if you're using IIS7 on Windows 2008, in addition to setting enableSessionState=true in your web.config, you have to put your modules inside the <system.webServer> section, instead of <system.web>. Changing this little thing solved it for me.
Why don't you try like this:
The Server.Transfer method also has a second parameter—"preserveForm". If you set this to True, using a statement such as Server.Transfer("WebForm2.aspx", True), the existing query string and any form variables will still be available to the page you are transferring to.
So I think doing like this your session will not expire.
Server.Transfer("~/Error.aspx?ErrorID=" + errorId,True);
The error you are encountering is because you are using a query string parameter. Per the msdn docs
However, the path parameter must not contain a query string, or ASP returns an error.
http://msdn.microsoft.com/en-us/library/ms525800%28v=vs.90%29.aspx
Its about 3/4 of the way down the page just above Requirements.
Even though the docs here are mentioning asp. and not asp.net, keep in mind the session state is a feature of IIS and is handled before asp.net is ever called.
#user2110845 : I had faced similar problem few months ago. the problem was with having an underscore in the website name. We were deploying a website in IIS with two different host names(adding two entries through the 'Edit Bindings' option on the website). The host names provided were abc_ts, abc_is. When the underscore was removed then the session problem got resolved.
It seems there are certain characters not allowed in a website host name. Check if that is your problem.
I found the answer here : link (check 'update 2' in the article)
You don't mention what version of ASP.NET you are using, but there were some changes between 2.0 and 3.5 in how unhandled exceptions bubbled their way up through an ASP.NET web app and then IIS.
Among some other possibles, while you are clearing the error you are not setting Context.Response.TrySkipIisCustomErrors = true; While this particular flag could have nothing to do with your issue (and is only available for 3.5+), it also could help deal with what is potentially two error pages behind the scenes that are obscuring the real issue. Regardless, it'll save you a lot of grief (at least if you are running 3.5+) with other potential issues. Check out two posts I wrote several years back that may be helpful: while they don't cover session handling, they do cover the multiple song-and-dance routines I had to follow to get proper 500 and 404 handling in various versions of ASP.NET. It's possible you will run into something that will get you further ahead, if not all the way there.
http://www.andornot.com/blog/post/Errors-Sending-the-Right-Message-(Redux-Covering-ASPNET-3540).aspx
http://www.andornot.com/blog/post/Errors-Sending-the-Right-Message.aspx

CryptographicException: Padding is invalid and cannot be removed and Validation of viewstate MAC failed

Monitoring my global exception logs this error seems to be impossible to remove no matter what I do, I thought I finally got rid of it but it's back again. You can see a strack trace of the error on a similar post here.
Notes about the environment:
IIS 6.0, .NET 3.5 SP1 single server ASP.NET application
Steps already taken:
<system.web>
<machineKey validationKey="big encryption key"
decryptionKey="big decryption key"
validation="SHA1" decryption="AES" />
In my Page Base for all of my pages
protected override void OnInit(EventArgs e)
{
const string viewStateKey = "big key value";
Page.ViewStateUserKey = viewStateKey;
}
Also in the source of the page I can see that all of the ASP.NET generated hidden fields are correctly at the top of the page.
First of all lets start from the fact, that this error of view state happens on PostBack.
Also I must say that I have done all the things that every one suggest to do to avoid this problem. And I have single machine, but 2 pools that run the same Pages.
So someone do an action, ether a man, ether some other search machine by 'clicking' on your pages, or some hacker try to check your system for problems...
I have similar problems (rare but existing ones), and I finally found that people try to hack-test my pages. (from the same IP I have and dos attacks)
I modify the function LoadPageStateFromPersistenceMedium() that translate the viewstate, and see by logging what exactly was the input, and from what IPs... then I started monitor these results and see that the view state was changed by hand - or was totally empty.
On error I just redirect him to the same page...
Here is what I did...
public abstract class BasePage : System.Web.UI.Page
{
protected override object LoadPageStateFromPersistenceMedium()
{
try
{
.. return the base, or make here your decompress, or what ever...
return base.LoadPageStateFromPersistenceMedium();
}
catch (Exception x)
{
string vsString = Request.Form[__VIEWSTATE];
string cThePage = Request.RawUrl;
...log the x.ToString() error...
...log the vsString...
...log the ip coming from...
...log the cThePage...
// check by your self for local errors
Debug.Fail("Fail to load view state ! Reason:" + x.ToString());
}
// if reach here, then have fail, so I reload the page - maybe here you
// can place somthing like ?rnd=RandomNumber&ErrorId=1 and show a message
Responce.Redirect(Request.RawUrl, true);
// the return is not used after the redirect
return string.Empty;
}
}
Second Reason
Now there is one more reason why this can happen, and the reason is because some one click on your page before the __EVENTVALIDATION is loaded.
This eventValidation is placed on the last button-even that asp.net found, and if you have some of them on many place on the page, or near the button, then this go to the end of the page.
So even if you see the viewstate on the top of the page, where is the Validation ??? maybe this never loaded - page corrupt ?, too fast user click on page ?
<input type="hidden" name="__EVENTVALIDATION" id="__EVENTVALIDATION" ... >
To avoid this kind of problem I made a simple javascript that I do not let it press the button unless this input have been loaded !!!.
One more comment, the __EVENTVALIDATION is not always presents ! so is maybe safer not to search for this field if you make a general solution, but to make a javascript trick to just check if the full page is loaded, or something else that you think.
Here is my final solution with jQuery: (note that I check on PageLoad if eventvalidation exist !). I have this placed on my MasterPages.
<script language="javascript" type="text/javascript">
function AllowFormToRun()
{
var MyEventValidation = $("#__EVENTVALIDATION");
if(MyEventValidation.length == 0 || MyEventValidation.val() == ""){
alert("Please wait for the page to fully loaded.");
return false;
}
return true;
}
</script>
protected void Page_Load(object sender, EventArgs e)
{
// I do not know if Page can be null - just in case I place it.
if (Page != null && Page.EnableEventValidation)
{
Form.Attributes["onsubmit"] = "return AllowFormToRun();";
}
}
You can test by placing near the button of your page a delay.
<% System.Threading.Thread.Sleep(5000); %>
Update
Today I see in log this message again for WebResource and what I discover is that a bot getting the pages and make all the character on the links in lower case, including the parameters, so this was one more reason to not getting the correct encoded string, and throw a message like Padding is invalid and cannot be removed.
Hope this help you more.
A survey of the web pages found with several of the keywords from the error message indicate that this type of error is relatively common, usually random (at least in appearance) and unfortunately rarely inclusive of an explicit work-around or explanation...
The existence of many similar-yet-different situations is probably tied to the very many different architectures and underlying configurations which can somehow lead to the inability of the crypto layer to assert the authenticity of the MAC (Message Authentication Codes) in the request pages:
Server farm setup
Cross domain / syndicated pages
third party widget libraries and such
Actual ASP program logic (of course)
One relatively frequent "marker" around these bug reports is the mention of resource requests (eg. WebResource.axd).
Note that such requests are often not logged (lest they inflate the log files size with event of relative little interest). This absence from the log file and the fact they are often cached (and hence the relative random and infrequent occurrence of the bug) may explain how this possible origin of the bug go "under the radar". This also suggests that in trying to recreate the bug, (while tracking in the logs, in real time etc) it may be useful to prevent the web browser from caching (or for the least to clear it cache initially).
In short, here are a few ideas and things to look for:
start logging the *.axd requests
try and co-relate such axd requests with the error events in the exception log
look for pages with resource references
if in a Farm setting, ensure that all instances use the same key (apparently the snippet provided in the question hint at multiple IIS servers)
Be suspicious of pages with 3rd party tie-ins (search services, affiliate programs...)
Hope this helps ;-)
Are you sure your problem is cryptography related, and not caused by oversized ViewState?
If ViewState is the problem, you can chunk it - change the value of pages / MaxPageStateFieldLength in web.config

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