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Cant go to the CMS. Bootstrapper.aspx not found


Hello all.

Need help with below issue.

I am picking up on a old project on CMS 11 for some fixes and when trying to load the CMS edit section, I get error as Bootstrapper.aspx not found. "System.ArgumentNullException: 'Value cannot be null.
Parameter name: UserName'".

Jun 21, 2022 0:19

Your logged in session might be struggling to load assets in the modules folder.


  • User you are logging in has an Administrator role? (This is assuming default roles haven't been modified)
  • Try creating a new admin user using whatever user manager has been setup against it. It'll either be membership or identity.
  • Check folders permissions if you're hosting in IIS
  • Reinstall nuget packages via package manager
Jun 21, 2022 10:47

Reinstallling the nuget packages worked for me. Thank you.

Jun 22, 2022 22:02
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