I have Organic Groups installed on my website. I have a content type with OG setting as Group. I had several contents of this type. And then all of a sudden, I started getting the following error when I try to create a content of this type:
Can't save entity as group, because user admin can't be subscribed to group and become a manager.
What may be causing this error?
You should change the number of value for the group_group field to unlimited. That field must be in the content type which you defined as group.
In my situation, it was caused by a recently deleted group still in the og_membership table. I had og field access enabled, and it was trying to determine if I had rights to write to the fields within the group. It didn't recognize the new node being created, so og searched through other groups my user was a member of to learn of my field rights. It saw a group in og_membership that technically didn't exist, and returned FALSE instead of null.
Anyway, this patch may help you: https://drupal.org/node/1538658#comment-8182821
Try it out! Disclosure: it's my patch :) If it works for you, make a comment in the drupal issue queue saying so.
Solution: Go to Configuration > People > Account Setting > Manage Fields > Edit Group membership Field > Scroll down to GROUP MEMBERSHIP FIELD SETTINGS and Make Number of value Unlimited > Save and Enjoy
