We are not able to replicate this problem. Here is what we did. Please tell us if you are doing things differently.
1. Created a new project with SF3.2.
2. Added some pages and content.
3. Created PageRSS service.
4. Using the hotfix blank project, upgraded the 3.2 database.
5. Logged in the administration and browsed to Administration->Services->RSS.
We were able to get to the Rss section.
A few suggestions though - have you made any changes to RSS database tables? These tables are:
As an option, you can back up your database, try to delete all content from these tables and create new Rss feeds. If anything goes wrong, you could restore your database with the backup.
We still want to find out the cause of this error. Perhaps it is some change in the 3.2 project, could you elaborate a bit more about any possible changes, or send us the web.config
Thank you in advance.
All the best,
the Telerik team