@mohammedodeh composer wouldn't apply the patch but when I changed the 3 lines across the 2 files I can now send messages, so it looks like the code works, just the patch didn't.
Here's the patch that I'm using, not sure if it's quite how you're meant to make them but composer applies it and it's working
I get this same error even when i just run drush cron manually.
I thought it needed a base_url in settings.php but that was removed in drupal 8
Ok, I have no idea is this is how patch files need to be in drupal but it applies correctly in composer.
So the problem is that function _opigno_forum_access returns false at the end. If the forum isn't attached to a group it should be affecting the permissions
I just came across this same bug. Opigno forums seems to be preventing access to all forums, and then if the user enrolls in a course they get access to that forum only.
Seems like a major bug to me but opigno doesn't use the /forum in the traditional way so i guess they don't really mind.
I do want to use /forum though so I'll have to figure out a work around
#2 worked for me, but agree that returning NULL might upset other code
#3 got rid of the warnings for me