Error or Document Not Found Page After Rebuilding the Indexes

This is for:

Developer System Administrator
In this article

Symptoms

After performing a rebuild of your indexes from the Indexing Manager (Sitecore Desktop > Sitecore Start Menu > Control Panel > Indexing > Indexing Manager), closing the window may redirect you to a Document Not Found or error page like this one:

Server Error in '/' Application.
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A potentially dangerous Request.Path value was detected from the client (:).
Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code.
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Exception Details: System.Web.HttpException: A potentially dangerous Request.Path value was detected from the client (:).
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Source Error:
An unhandled exception was generated during the execution of the current web request. Information regarding the origin and location of the exception can be identified using the exception stack trace below.
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Stack Trace:
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[HttpException (0x80004005): A potentially dangerous Request.Path value was detected from the client (:).]
   System.Web.HttpRequest.ValidateInputIfRequiredByConfig() +12352359
   System.Web.PipelineStepManager.ValidateHelper(HttpContext context) +166
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Version Information: Microsoft .NET Framework Version:4.0.30319; ASP.NET Version:4.0.30319.34212

Cause

The admin session has expired and Sitecore won’t allow you to continue using the Control Panel until you sign in again. The error page is simply the result of a badly formatted URL inside Sitecore.

Resolution

Just head back to the Sitecore Login page to re-enter your credentials. The indexing process was most certainly performed correctly.