Failure in loading assembly (Event ID:6611)

I was receiving the following error in the event log:

Error: Failure in loading assembly: <assembly name>, Version=<version number>, Culture=….

 

The <version number> in the above error was for the previous version of the affected SharePoint solution.
Although the current version of the solution seemed to be working fine, the above error kept popping up in the event logs. I eventually found the culprit. It was a ‘SafeControl’ entry in the web.config file.

We removed the entry from the web.config file and since then there have been none of these errors logged.