SharePoint 2007 Forms Server

Right now I’m troubleshooting a mysterious error that one of my support customers is experiencing using InfoPath forms on a SharePoint site. The users are entering information into a browser enabled form, taking a really long time, and I’m pretty sure there’s a session timeout happening. What’s mysterious is that I can’t reproduce the error exactly by opening a form and letting the session time out, then attempting to save it. I get a completely different error. So there must be more at play.

My current working theory is that there are 2 separate (but possibly related) issues happening at the same time. One error when the user attempts to save the form (resulting in the loss of all their changes), and one when the browser attempts to reload/display it (resulting in the error message shown and the inability to go back to a view of the form with their updated content).

Here are some sanitised error messages I’ve captured from the event log when the problem happens.

InfoPath Forms Services has detected a mismatch between the user's data in the browser and on the server. This may indicate the SESSION_STATE_PASCAL_CASED is not configured properly on a multiple front end farm or that a malicious user is trying to tamper with client data. (User: DOMAIN\username, Form Name: Form, IP: , Request: http://website/_layouts/FormServer.aspx?XmlLocation=/filepath.xml&Source=http://website/Library/Forms/AllItems.aspx?RootFolder=%&FolderCTID=0x0120004AE5D17103937E4DAC784D461AF8C33D&View=%257b9AD631DA%252d5EDE%252d4EF1%252d8FF3%252d14ED56F1471A%257d&DefaultItemOpen=1, Form ID: urn:schemas-microsoft-com:office:infopath:Form:-myXSD-2009-09-01T01-30-36) 604f4e9e-bff3-460d-af19-229411e20ab9

WARNING: Invalid Canary for view file. StackTrace: at Microsoft.Office.InfoPath.Server.Controls.ResourcePage.GetSolutionAndVerifyCanary(HttpContext context, String solutionId, SPSite contextSite, ResourceErrorType& error) at Microsoft.Office.InfoPath.Server.Controls.ResourcePage.HandleViewFile(HttpContext context) at Microsoft.Office.InfoPath.Server.Controls.ResourcePage.<>c__DisplayClass2.b__0() at Microsoft.Office.Server.Diagnostics.FirstChanceHandler.ExceptionFilter(Boolean fRethrowException, TryBlock tryBlock, FilterBlock filter, CatchBlock catchBlock, FinallyBlock finallyBlock) at Microsoft.Office.InfoPath.Server.Controls.ResourcePage.ProcessRequest(HttpContext context) at System.Web.HttpApplication.CallHandlerExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute() at System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously) at System.Web.HttpApplication.ApplicationStepManager.ResumeSteps(Exception error) at S

Don’t you love how that last stack trace just gets cut off like that? Woo!

Here is my current link log from researching the issue:

• Reading this now: http://blogs.msdn.com/b/shivajin/archive/2009/05/11/deep-dive-on-infopath-request-and-response.aspx
• This describes the error message I can’t reproduce. I’ve already verified that AAM isn’t the problem, the users are accessing the site via the Default Zone URL. http://social.msdn.microsoft.com/Forums/en-US/sharepointinfopath/thread/1729d3eb-b63f-462d-bbb6-53a735ad6b98/
• This could be more likely. All service accounts are domain accounts, but I do know that our client’s infrastructure had some odd AD policies that might be occasionally wreaking havoc somehow. http://blog.sharepointrx.com/2010/02/05/infopath-forms-server-error-there-has-been-an-error-while-loading-the-form-a-required-resource-could-not-be-downloaded-to-try-to-resume-the-download-refresh-the-page/
• This is also likely but I hope it’s not the case. Having people delete their temporary internet files is not going to really help the problem much if they’ve just lost an hour’s worth of work in their form. Even though this is ostensibly a workflow issue, the workflow forms are InfoPath, so it could be related. http://www.dev4side.com/community/blog/2010/6/11/error-there-has-been-an-error-while-loading-the-form-in-an-approval-workflow.aspx
• This one also suggests a caching/temporary files issue might be causing this. No, no! It can’t be true. Also, further reading indicates the suggestion to run stsadm -o reconvertallformtemplates is a really bad idea. http://vspug.com/ssa/2007/12/24/tip-session-state-pascal-cased-is-not-configured-properly/
• Once again suggesting IE’s caching is at fault: http://blog.jussipalo.com/2008/02/forms-server-invalid-canary-for-view.html
• More info on what the “Invalid canary” warning means: http://social.technet.microsoft.com/Forums/en/office2010/thread/0acbb4e3-4526-487d-8f67-781cc3bb63b1
• This post suggests SP2 will fix things… except the environment is already running SP2. Bother. http://blog.sharepointalist.com/2009/10/invalid-canary-for-view-file.html

My conclusion is that there is some type of caching, cookie expiry, session timeout bad juju going on. Unfortunately that’s not one I can document for an end user!