Looks like a reference issue for how you are storing your container contentsm, and it not being available to a certain user, and there's another thread bookmarked with people having the same issue (I think you posted there as well).
There are lots of threads about it.
At this point I am the only user of the database. The files are stored externally but not secured. They are indeed in the folders they' re supposed to be and
fmserver as well as fmsadmin have read & write access, so that's ok.
It was a fresh install, everythings's working fine except the 'Export Field Contents' on the WebDirect side. It's working with a Filemaker client without any problem.
I even don't know where to start looking for. Filemaker? Apache? Is php involved? Java?
And it isn't working in FireFox and Chrome either.
Has there been any resolution to this problem. I am experiencing the same thing. FileMaker Client works fine, WebDirect gives the error you have shown in your original post.