Unable to install 30 Trial of Plumsail: 500 Internal Server Error

System is SharePoint Online.

Install fails with: 500 Internal Server Error. From there I proceeded to install the Addon directly into SharePoint. Was successful in placing the app in a site. The app though, did not work. Just sat there looking pretty in the Site Contents.

Sorry if this is a duplicate but I only found one reference to this error. The circumstances were different.

Any help greatly appreciated.



Hello! I will consult with developers regarding your issue and will post the result here.

Hello! The developers will work on solving the issue but it will take a while. As a workaround, please create a team site manually, install a classic version of HelpDesk on it, go to the "About" page in settings and update the product to the latest version.

This worked - Thank you very much!

Spoke to soon - the update to modern pages fails with:

Okay, so I managed to get this installed. Not fun:


  1. Had to install as a new sub-site.
  2. A public CDN was a requirement in my case.
  3. Had an old classic version as the base from which to begin.

a) the parent site had to be present - would not install as a site collection root.
b) the parent had to be a modern page for the upgrade to complete.

Any way, happy trails...

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Thank you for the update! The developers are working now on fixing the error you encountered so in future, it won't required such difficulties with the installation.