Error upgrading from 10.1-RELEASE to 10.2-RELEASE

[Maurizio Vairani]

Hi,
I am trying to update an amd64 system. With the command:
# freebsd-update upgrade -r 10.2-RELEASE
I receive the error:
....9510....19520....19530....19540....19550....19560....19570....19580....19590 
done.
Applying patches... done.
Fetching 13651 files... 
1ae3b1c9f35d65ced43103718a87a4201f4e3434160114a0d355bbf5284da6aa has 
incorrect hash.

Note: running
# freebsd-update fetch
I receive this message:
The following files are affected by updates, but no changes have
been downloaded because the files have been modified locally:
/var/db/mergemaster.mtree

but I do not know if it is related to the error above.
Thanks
Maurizio