Documents no longer working after upgrade from SugarCRM

Hi,

I recently upgraded from SugarCRM to SuiteCRM 7.7.5

Documents no longer open. when I click on the file name, I receive the following error message in Edge:

HTTP 500 error
That’s odd… the website can’t display this page
The site may be undergoing maintenance or could have a programming error.
Try this
Go back to the last page

In Chrome, the error message is:

The XXX.45.185.XX page isn’t working

XXX.45.185.XX is currently unable to handle this request.
HTTP ERROR 500

Any help is greatly appreciated.

Thanks

Joe