During various search troubleshooting i came across the following crawling error in the Crawl log of a SharePoint 2013 environment.
Processing this item failed because of an unknown error when trying to parse its contents. (Error parsing document ‘http://********.*****.com/Project/abcd/Q_M/ABX/SitePages/Homepage.aspx’. Sandbox worker pool is
closed.; ; SearchID = *******************)
In order to fix this you can try to perform the following action plan:
Open “Local Policies”
Click on “User rights assignment”

Make sure that the search service account has the following rights:
“Replace a process level token”

“Adjust memory quotas for a process”

“Impersonate a client after authentication”

Please make sure that the policies don’t get changed afterwards.
After implementing the above changes please run a clear configuration cache
After clearing the cache, start a full crawl and the errors should be gone.



