Despooler received an instruction and package file from site %1 that contains that site's public key, however the despooler ...

%11Despooler received an instruction and package file from site %1 that contains that site's public key, however the despooler cannot find a valid public key to verify the signature of the package.  Because this site does not allow unsigned key exchange between sites, the instruction cannot be processed and will be retried.

Solution: Extend the Active Directory schema to allow ConfigMgr sites to publish their public keys into AD, or use the preinst.exe tool to manually replicate the public keys, or change the site property site connection setting in the Administrator UI to allow unsigned key exchange between sites.%0