Nextcloud only stores a checksum which is supplied in the OC-Checksum
header of an upload, and discards it again when the modification time
is set with PROPPATCH. Re-sending the checksum in the PROPPATCH (as is
done for ownCloud) is rejected by Nextcloud with 403 Forbidden which
made the whole PROPPATCH fail, so SetModTime returned an error on any
object which had a hash. Uploads from sources without hashes, eg
streamed uploads with `rclone rcat`, were stored with no hash at all.
Use the Nextcloud PATCH extension with the X-Recalculate-Hash header
to have the server calculate and store the SHA1 of an object after a
streamed upload and after setting the modification time. This gives
a server side hash of the stored data which also lets rclone verify
streamed uploads.
Nick Craig-Wood
f7c510af49