title: Error: Cannot add the specified assembly to the global assembly cache:Select.Pdf.dll
body: <p>I add licensed select.pdf.dll to my SharePoint project. This dll file has added in both the visual studio reference and the package section(Deploy target as 'Global Assembly Cache (GAC)').</p>
  
  <p>I was not able to deploy my solution to my sharepoint development server, with the error message</p>
  
  <p>“Error occurred in deployment step 'Add Solution': Error: Cannot add the specified assembly to the global assembly cache: Select.Pdf.dll.”</p>
  
  <p>I have googled the problem, someone cannot deploy because the .dll they want to deploy already existed in %windir%\assembly folder and the .dll is locked by other process. 
  <a href="https://stackoverflow.com/questions/36336536/vs2015-build-error-cannot-add-the-specified-assembly-to-the-global-assembly-cac">VS2015 build error: Cannot add the specified assembly to the global assembly cache</a>
  <a href="https://devramblings.wordpress.com/2011/03/23/error-cannot-add-the-specified-assembly-to-the-global-assembly-cache/" rel="nofollow noreferrer">https://devramblings.wordpress.com/2011/03/23/error-cannot-add-the-specified-assembly-to-the-global-assembly-cache/</a></p>
  
  <p>However, the "Select.Pdf.dll" I want to deploy has never been deployed before, the %windir%\assembly and %windir%\Microsoft.Net\assembly folders do not have same name dll. file in them.</p>
  
  <p>I have tried to restart VS, and reset IIS. the problem still existed.</p>
  
  <p>Is there any way to solve the problem? Thank you.</p>