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If you are wondering why you are getting the following pop-up screen when attempting to edit a procedure (or a trigger, a type or anything else that can be edited in the editor panel, but not views for instance) after upgrading to the latest version of SQL Developer (1.5.4)...
ORA-00904: "ATTRIBUTE": invalid identifier
vendor code 904
... you may ask yourself if you are trying to perform this operation on a Oracle 9i database.
Please note that the annoying pop-up message doesn't prevent you from editing the source and apparently you can still compile it successfully, although every time you hit on the compile icon you'll get the exception again.
It looks like a problem with some underlying view or table that is queried by SQL Developer and is lacking a column in oracle 9i, but this is just a speculation of mine.
Initially i had a feeling that someone had told me that as of version 1.5.x Oracle 9i was no longer supported, but when i read the release notes i read that Oracle 8.1.7 was no longer supported, so i failed to find a specific statement about Oracle 9i.
I must conclude that it is still supported or i did not search hard enough in the accompanying documentation...
If i click on EDIT using SQL Developer 1.5.1 (the previous version installed on my PC) i don't get any errors of this kind.
See message translations for ORA-00904 or read more articles about SQL Developer.