That's why CPDN had problems with the 5.4.9 release and nobody else did - the project is hosted over two sites (OU + Oxford) and three domains, and over time several alternate URLs were accepted and in common use. Along comes an update which both validates it and also doesn't have any mechanism for migrating alternate URLs into the master URL, and *bang*!

Don't complain if you don't know. BOINC allows the scheduler, file upload handler, and individual file downloads to have all completely different URLs. SETI is also separated in different servers and domains. Einstein@Home has a list of 20 URLs for each file (differing only on domain name) to make the client download from a random one.

The problem is with multiple URLs taking to the same place, and some people attaching with one URL, other people using another... The *project master URL* has to be unique.