Precondition failed (HTTP 412) when rerunning sync to mailbox.org

[joelpet]

Report

Steps to reproduce

1. Sync from Google to local
2. Sync from local to Mailfence
3. Repair unsafe UID on Mailfence
4. Wipe out local (store and status)
5. Sync Mailfence to local
6. Sync local to Mailbox (with manual throttling through KeyboardInterrupt)

Expected behavior

• Items are uploaded to Mailbox until keyboard interrupt (Ctrl-C).
• Then, when sync is resumed (rerun), some more items are uploaded.
• Finally, there is nothing left to sync and it exits successfully.

Actual behavior

• Items are uploaded to Mailbox until keyboard interrupt.
• Then, when sync is resumed (rerun), there are conflicts, despite no concurrent modification from other clients.

System details

• Your vdirsyncer version: 0.16.4
• If applicable, which server software (and which version) you're using: Google, Mailbox, Mailfence
• Your Python version: 3.6.5
• Your operating system: Arch Linux \r (\l)
• Your config file: config.txt
• Use vdirsyncer -vdebug for debug output. vdebug.txt

Example

The item 00150f4f-5342-4cea-9fff-89d9af72ebcc.ics:

Copying (uploading) item 00150f4f-5342-4cea-9fff-89d9af72ebcc to mailbox_calendars/50
debug: Normalized URL from '00150f4f-5342-4cea-9fff-89d9af72ebcc.ics' to '/caldav/50/00150f4f-5342-4cea-9fff-89d9af72ebcc.ics'
debug: PUT https://dav.mailbox.org/caldav/50/00150f4f-5342-4cea-9fff-89d9af72ebcc.ics
debug: {'User-Agent': 'vdirsyncer/0.16.4', 'Content-Type': 'text/calendar', 'If-None-Match': '*'}
/.../
debug: Sending request...
debug: 412
debug: {'Date': 'Thu, 24 May 2018 21:20:11 GMT', 'Server': 'Openexchange WebDAV', 'X-Robots-Tag': 'none', 'Content-Length': '0', 'Strict-Transport-Security': 'max-age=15768000', 'Keep-Alive': 'timeout=5, max=98', 'Connection': 'Keep-Alive', 'Content-Type': 'text/calendar'}

error: Unknown error occured for calendars__local__mailbox/main: Precondition Failed

Resources

• https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/If-None-Match
• https://developer.mozilla.org/en-US/docs/Web/HTTP/Status/412

[untitaker]

This looks like misbehavior on Mailbox's side.

At least in the last run, e.g. the item 013bc1ca-81b6-43e1-9d39-9abf1cf8d336 is not reported in the "directory listing" for your calendar, but it is reported as conflicting with the item we want to upload.

I would get in touch with them if they can investigate your account.

[joelpet]

Thank you very much for looking into this. I have now contacted Mailbox.org and I am waiting for their reply.