[GH-ISSUE #228] All remote events deleted when "Use WebDAV collection sync" is not checked #1124

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opened 2026-03-14 00:22:52 +03:00 by kerem · 2 comments

kerem commented

2026-03-14 00:22:52 +03:00

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Originally created by @gtebbutt on GitHub (May 10, 2018).
Original GitHub issue: https://github.com/aluxnimm/outlookcaldavsynchronizer/issues/228

System has been set up and working well for around 6 months, with bidirectional sync for two Google calendars (one personal, one shared) + contacts to Outlook 2016. One or two events were wiped from Google a few months ago, but we assumed user error and left it at that.

Last week, all future events were wiped from both Google calendars, and cancellation notices were sent to all invitees. Events remained in Outlook. Any new events added to the Google calendars via the web interface or other software would be wiped again on the next Outlook sync; new events added to Outlook would remain locally but not sync.

After some trial and error, checking "Use WebDAV collection sync" (which was unchecked) fixed the issue and re-synced everything back to Google (sending new invites to everyone in the process). As far as I'm aware, this wasn't checked initially, and none of the advanced settings had been changed - I only even found the "Advanced Settings" option as a result of trying to debug this issue.

Happy to provide any info or logs if needed - just let me know what would be useful and where to find it!

Originally created by @gtebbutt on GitHub (May 10, 2018). Original GitHub issue: https://github.com/aluxnimm/outlookcaldavsynchronizer/issues/228 System has been set up and working well for around 6 months, with bidirectional sync for two Google calendars (one personal, one shared) + contacts to Outlook 2016. One or two events were wiped from Google a few months ago, but we assumed user error and left it at that. Last week, all future events were wiped from both Google calendars, and cancellation notices were sent to all invitees. Events remained in Outlook. Any new events added to the Google calendars via the web interface or other software would be wiped again on the next Outlook sync; new events added to Outlook would remain locally but not sync. After some trial and error, checking "Use WebDAV collection sync" (which was unchecked) fixed the issue and re-synced everything back to Google (sending new invites to everyone in the process). As far as I'm aware, this wasn't checked initially, and none of the advanced settings had been changed - I only even found the "Advanced Settings" option as a result of trying to debug this issue. Happy to provide any info or logs if needed - just let me know what would be useful and where to find it!

kerem commented

2026-03-14 00:22:58 +03:00

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@nertsch commented on GitHub (May 10, 2018):

Please post the logfile

@nertsch commented on GitHub (May 10, 2018): Please post the logfile

kerem commented

2026-03-14 00:23:03 +03:00

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@gtebbutt commented on GitHub (May 11, 2018):

These appear to be the relevant sections, although they sadly don't seem to provide a lot of insight as far as I can see. No errors or anything, and the re-addition happened of its own accord when I checked "Use WebDAV collection sync".

deletion_log.txt
re_addition_log.txt

My only working theory is that perhaps there was some issue with time windowing (although to the best of my knowledge it wasn't enabled), since the number of events in the deletion log is much smaller than the number re-added.

@gtebbutt commented on GitHub (May 11, 2018): These appear to be the relevant sections, although they sadly don't seem to provide a lot of insight as far as I can see. No errors or anything, and the re-addition happened of its own accord when I checked "Use WebDAV collection sync". [deletion_log.txt](https://github.com/aluxnimm/outlookcaldavsynchronizer/files/1994897/deletion_log.txt) [re_addition_log.txt](https://github.com/aluxnimm/outlookcaldavsynchronizer/files/1994898/re_addition_log.txt) My only working theory is that perhaps there was some issue with time windowing (although to the best of my knowledge it wasn't enabled), since the number of events in the deletion log is much smaller than the number re-added.