Syncthing 1.2.0 and newer do not interoperate with 0.14.45 and older - 18/07/2019 00:00 GMT

Starting with version 1.2.0, Syncthing always uses large, variable-sized,
blocks to index and transfer files larger than 256 MiB [1]. Syncthing
version 0.14.45 and older will initially appear to accept files scanned
with large blocks, but will later panic and shut down during some internal
file operations. Do NOT install those versions, or enable large blocks in
older versions, in clusters with devices still on v0.14.45 or older,
e.g. Debian Stretch servers using distribution-provided packages.

[1] https://docs.syncthing.net/advanced/folder-uselargeblocks.html