Getting "ERROR: CRRRS5302E Error: HTTP/1.1 404" when trying to create a RRC project after migrating to 4.0

We have migrated our CLM tools from 3.x to 4.0. In RRC, both the project areas and the process templates were migrated.
Now, I want to create a new RRC project, using a RRC process template involved in the migration, but I am getting an error when the creation process tries to apply the template.
The error messages says:
                ERROR: CRRRS5302E Error: HTTP/1.1 404
The project is created anyway, but the structure is bad (no artifact types, folder structure empty, and so on).

Any ideas?
--Claudia