can no longer forward emails

We upgraded to the latest version and while some issues have gone away others are still there. One such thing is that we can no longer forward emails. Or rather the issue is that the body is shown as a blank text field and when sending out the email there is nothing in except fo any text I am writing into the text field. Looking at the log file I am seeing a lot of these errors:

[ERROR] Unable to find relationship emails_email_templates

[ERROR] Unable to load custom logic file: custom/include/social/hooks.php

Does anyone have an idea what’s wrong? All of this used to work before we started upgrading on the 7.9.x branch.
thx for any suggestions

Was able to remove one error in the log file:
[ERROR] Unable to load custom logic file: custom/include/social/hooks.php

I downloaded the full install and copying the hooks.php file which suite was complaining to the diretory. Why this file was missing is beyond my understanding. The error no longer shows, but the issue is still there. So, this seems not to have been the cause.

Found the issue. It seems that the cache was causing all these issues. I am not sure if after the upgrade the cache should have been cleared. In any event I have now disabled the cache and everything is working like a charm again.
For those who are interested on how to clear the cache:

navigate to Admin -> System Settings and turn in Developer Mode ensuring you also run a Quick Reair & Rebuild to clear any previous cache.