On our site we use XForm for form implementations. We did some upgrades to EPIServer dll's and now we get an error we trying to select another form:
An object or column name is missing or empty. For SELECT INTO statements, verify each column has a name. For other statements, look for empty alias names. Aliases defined as "" or  are not allowed. Change the alias to a valid name.
I tried to revert the DLLs back to the latest working version but the error remains.
Between which versions?
These are the dlls that were changed (and now reverted). Green is current installed version, red is newest version.
Don't forget the database schema can get updated through versions too so you could try rolling back to a back up version of the DB from before the upgrade.
Thanks for your comment. The DB updates are done manually and were not necessary in this upgrade.
Some seemingly random uninstalls / installs of EPIServer dll's fixed my problems. Not a very satisfying solution.
Probably a dll with wrong version somewhere then...