v4.1.1 has just been released - this patches a small issue recently discovered and fixed.
We identified an issue involving older nodes (v4.0.0)syncing against more recent v4.1.0 nodes. This is related to the conversion logic between v2 and v3 blocks to support CommitOnly transaction inputs.
(Brief) release notes available here - https://github.com/mimblewimble/grin/releases/tag/v4.1.1
If anybody is running a v4.1.0 node we recommend updating to v4.1.1 when convenient.
If anybody is still running a v4.0.0 node then this might be a good time to upgrade to v4.1.1 also.
Enjoy!