After upgrade or uninstall BoostSolutions products, there might be some invalid event receivers left which will cause error messages as belows:
Event manager error: Could not load file or assembly ‘BoostSolutions.xxxx, Version=188.8.131.52, Culture=neutral, PublicKeyToken=15fd9ef9a2ec3a95′ or one of its dependencies. The system cannot find the file specified.
The issue is caused that some invalid event receivers haven’t been removed completely.
Please see the PDF article.
Applies for: SharePoint 2013, SharePoint 2010, SharePoint 2007