by Howard Gaukrodger.
Hi Marian, I used your good advice to part-solve the same problem on my site, but I had to edit slightly different lines, as follows.
1. Do not edit line 238
2. Edit line 242 and line 249 to use your solution as follows:
$joining = bigbluebuttonbn_view_joining( $bbbsession );
Lines 242 and 249 are the same, so I have just entered your solution at the beginning.
My site now works, so thanks again for your solution. I hope my tweak helps a few more people.
Regards.