Due to some incompatibility with one or more blocks created on or after 12 July 2022, v1.x versions are apparently incompatible and will fail with

EXCEPTION: 11DbException
Db::put: Cannot allocate memory

The exact cause of the problem is not known, but it's something which has been reported with other blockchains where very old versions are used.

The fix for this is to upgrade to v2.0

At the time of the failure, there were only three known peers on the whole network using v1.x, and one of those has been upgraded to v2.0 which leaves only two of them.