REPL2OLD, Instance IIII uses a GT.M version that does not support connection with the current version on iiii.
MUPIP Error: Issued by a Source Server, Receiver Server or MUPIP JOURNAL -ROLLBACK -FETCHRESYNC on Instance iiii attempted to connect to instance IIII, but found IIII is running an earlier version that does not support the current replication protocol. This can indicate either that the older version is just too old for any connection with the newer version (in case the older version is less than V5.1-000) or that the older version doesn't have the logic required to support a Supplementary Instance (in case the older version is less than V5.5-000). Note that IIII may not be available if the older instance uses a version of GT.M less than V5.1-000.
Action: Upgrade the GT.M version on IIII to a version that can support communication with the current version or, if this is a Supplementary Instance, that can deal with a Supplementary Instance or choose another appropriate instance for the connection.
