I have created new managed metadata service (with new database and application pool) and after that I am not able to search content with the error
"Search has encountered a problem that prevents results from being returned. If the issue persists, please contact your administrator."
I also add new application pool for default managed metadata service because with the existing application pool I get error
"The Managed Metadata Service or Connection is currently not available. The Application Pool or Managed Metadata Web Service may not have been started. Please Contact your Administrator".
This issue is fixed after adding new application pool but Search is still not working with the same error.