I just encountered this error when trying to add a new item to our site. I have never had this problem before. I have seen a couple of postings about this issue, but both appear to be closed. One posting indicated that the archive/theme_uploads directory needed to be writable. We have made this directory writable, but the problem remains.
Would someone who has solved this problem let me know what the solution is?
I am using Omeka v.1.2