I get that a lot as I’ve been updating a lot of old mods. I assumed it’s just re-assigning ID numbers for the new versions. I have not found it to have any effect, or create any errors, on the mods operation. Am I guessing correctly?
They are not errors. There was a bug where the replacement pieces defined inside Place/Replace Other trait definitions where not being allocated GPID’s.
The result was that pieces created by the Place/Replace traits could not be updated by the GamePiece Refresher.
These messages are just reporting that the GPID’s for these components are being update from (nothing) to a new value.
You will also see these sort of messages if you hand edit the buildfile and add new piece definitions manually. It is just Vassal cleaning up the mess.
This should always be a one-off when you first edit the module after manually editing the buildfile, or with the version of Vassal that fixed the Place/Replace GPID bug. When you save the module, the updated GPID’s are saved with the module. If you see these messages on an ongoing basis, then let us know.