When I click on new calendar button in calendar overlay page, I always get this error:


An unexpected error has occurred.

Troubleshoot issues with Microsoft SharePoint Foundation.

Correlation ID: 3c0a60f1-6ceb-425c-81c1-0556c43b3070

Date and Time: 5/13/2015 10:47:58 AM

I have two different calendar in my site and they both got this same error when I attempted to add new calendar overlay, can someone tell me what is causing this error?

UPDATE: LOG files message filtered by this correlation ID:

  • System.IO.FileLoadException: Loading this assembly would produce a different grant set from other instances. (Exception from HRESULT: 0x80131401)
    at Microsoft.SharePoint.Utilities.ThmxTheme.Open(Stream stream, FileMode mode, FileAccess access)
    at Microsoft.SharePoint.Utilities.ThmxTheme.Open(SPFile themeFile, Boolean readPublishedVersion, FileMode mode, FileAccess access)
    at Microsoft.SharePoint.Utilities.ThmxTheme.Open(SPSite site, String url)
    at Microsoft.SharePoint.ApplicationPages.AggregationCustomizePage.InitializeDropDownListItems()
    at Microsoft.SharePoint.ApplicationPages.AggregationCustomizePage.CreateChildControls()
    at System.Web.UI.Control.EnsureChildControls()
    at System.Web.UI.Control.PreRenderRecursiveInternal()
    at System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint)

I'm still unsure about what is causing the error after reading the message.

  • You need to check the uls logs for details information....
    – Waqas Sarwar MVP
    May 13, 2015 at 14:58
  • You need to investigate it further using the SharePoint log.The tool that you need would be the ULS Viewer over here microsoft.com/en-ca/download/details.aspx?id=44020. Select File->Open From->ULS and it will start tracking your log in real time. Reproduce the error, get the correlation id and filter the log by it. Look for the Unexpected or Critical Level events. These are the errors that have occurred. This will give you the idea of what actual error you are facing. May 13, 2015 at 15:36
  • thanks for the help, I'm trying to gain access to the server where sharepoint is installed.
    – SSilicon
    May 13, 2015 at 15:50
  • Please post your update as an answer and chose it as your preferred answer. That way this question will get a resolved state May 14, 2015 at 15:32

1 Answer 1


The problem is fixed after I restarted the computer, such a shame I didn't try that earlier. I'm still unsure about the cause of the error though.

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