As I wrote above, I didn't upgrade further because of the Postgresql version my new server is running:
"I stopped upgrading at OpenACS 5.2.3 as I am using Postgresql 7.4"
I used Postgresql 7.3 on the old server to move from OpenACS 4.6.3 to 5.2.3 and then moved the code and database to the new server running Postgresql 7.4. Is there a page summarising the improvements in the different versions?
According to the compatibility matrix ( https://openacs.org/xowiki/openacs-compatibility-matrix ) to upgrade from OpenACS 4.5, you first need to run Postresql 7.2 to upgrade to OpenACS 4.6.3, and then
run Postgresql 7.3 to upgrade from OpenACS 4.6.3 to OpenACS 5.2.x. And then Postgresql 8.x to upgrade beyond that.