SharePoint error: "Failed to find ACL for ScopeId: b19c18cd-34a7-4c2d-aca7-557039b3a156"

I got this error message from ULS log when trying to download an image file from a document library. Don't see any other problem and just cannot download the image file.

It turns out quite simple: SharePoint generated a lot of "Policy Usage Report" files (15k+) in "UsageReports" document library. After deleting these files, the problem disappeared.

Below are the error message I got from the web page.


Server Error in '/' Application.
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Cannot complete this action.

Please try again.0x80004005 
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. 

Exception Details: System.Runtime.InteropServices.COMException: Cannot complete this action.

Please try again.0x80004005

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.  

Stack Trace: 

[COMException (0x80004005): Cannot complete this action.

Please try again.0x80004005]
   Microsoft.SharePoint.Library.SPRequestInternalClass.GetAclForScope(String bstrWebUrl, Guid guidScopeId, Boolean fRequirePermissionCheck, Object& pvarAcl, UInt64& lAnonymousMask) +0
   Microsoft.SharePoint.Library.SPRequest.GetAclForScope(String bstrWebUrl, Guid guidScopeId, Boolean fRequirePermissionCheck, Object& pvarAcl, UInt64& lAnonymousMask) +183

[SPException: Cannot complete this action.

Please try again.]
   Microsoft.SharePoint.SPGlobal.HandleComException(COMException comEx) +27861714
   Microsoft.SharePoint.Library.SPRequest.GetAclForScope(String bstrWebUrl, Guid guidScopeId, Boolean fRequirePermissionCheck, Object& pvarAcl, UInt64& lAnonymousMask) +28084291
   Microsoft.SharePoint.SPReusableAcl..ctor(SPRequest request, String webUrl, Guid scopeId, Boolean requirePermissionCheck) +74
   Microsoft.SharePoint.SPSite.GetReusableAclForScope(Guid scopeId) +98
   Microsoft.SharePoint.Publishing.<>c__DisplayClass3f.b__39() +203
   Microsoft.SharePoint.<>c__DisplayClass4.b__2() +729
   Microsoft.SharePoint.Utilities.SecurityContext.RunAsProcess(CodeToRunElevated secureCode) +26712342
   Microsoft.SharePoint.SPSecurity.RunWithElevatedPrivileges(WaitCallback secureCode, Object param) +27759977
   Microsoft.SharePoint.SPSecurity.RunWithElevatedPrivileges(CodeToRunElevated secureCode) +93
   Microsoft.SharePoint.Publishing.BlobCache.HandleCachedFile(HttpContext context, BlobCacheEntry target, Boolean anonymousUser, SiteEntry currentSiteEntry) +2184
   Microsoft.SharePoint.Publishing.BlobCache.RewriteUrl(Object sender, EventArgs e, Boolean preAuthenticate) +3917
   Microsoft.SharePoint.Publishing.PublishingHttpModule.AuthorizeRequestHandler(Object sender, EventArgs ea) +56
   System.Web.SyncEventExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute() +80
   System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously) +171

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Version Information: Microsoft .NET Framework Version:2.0.50727.5466; ASP.NET Version:2.0.50727.5456 

[update 20130701]

1. Another possible The solution is to reset all cached blob files. We can find the file location by this post, and then delete all sub-folders there.
2. In terms of the post here, you can try to flush the object cache if the fix above doesn't work.