"Cannot add the specified assembly to the GAC in SharePoint 2010" WSP Solution deployment error
Error : "Cannot add the specified assembly to the GAC in SharePoint 2010" We had a solution deployed numerous times as it houses a line of business process in SharePoint 2010. On performing Upgrade Solution via stsadm or Update-Solution via Power Shell , encountered the error: cannot add the specified assembly to the GAC. We started by created a test solution package and deployed it on the environment which worked fine to identify whether the issue was with the Package or environment. On updating the LOB Solution , it couldn’t add the assembly to the GAC for LOB WSP, on one of the WFE servers. Performed an IISRESET and restarted the timer service on the failing WFE, deployed the WSP package again, it did work but when we tried updating it again at the later stage, got the same error. Solution : I had to rely on Process Explorer to figure out what process was using the DLL and from where. The beauty of this tool is, it displays the list of processes ru