S3Drive - Proton Drive two-way sync fails

Hello, I set up a two-way sync between my Proton Drive remote storage and a local folder. Files are being downloaded but sync seems to fail every time. I went through the logs and noticed these entries (there are more that are similar, for each time a sync attempt is being made): #6 Sync exponential fallback delay. Failed 2 time(s). Delay: 0:00:25.000000. Next try: 2025-08-18 07:15:13.321796.

#7 Sync failed. Exception: bisync aborted. Stack: *** *** *** *** *** *** *** *** *** *** *** *** *** *** *** ***
pid: 25198, tid: 486336066808, name 2.ui
os: android arch: arm64 comp: yes sim: no
build_id: 'e4f372b4ed9db5697653648df01aff3d'
isolate_dso_base: 6d23058000, vm_dso_base: 6d23058000
isolate_instructions: 6d2347e880, vm_instructions: 6d23468000
    #00 abs 0000006d23de407f virt 0000000000d8c07f _kDartIsolateSnapshotInstructions+0x9657ff
<asynchronous suspension>
    #01 abs 0000006d23de0a1f virt 0000000000d88a1f _kDartIsolateSnapshotInstructions+0x96219f
<asynchronous suspension>

Version is 1.14.7, running on Android 13 Is there anything that can be done about this? Thanks (edited)

Thanks for your report. How do you start your sync? Does it start automatically in the back-ground or perhaps you open the app and e.g. click Sync start? When your sync runs, do you wait for it to finish with an app opened or perhaps navigate to other apps? Did you disable battery optimizations? (In the Sync screen if you see orange battery icon, you should click on it). In principle when your sync starts in the foreground (e.g. you started the app), then it might not always be able to finish when you move the app to taskbar. Once sync starts in the background, in most cases it shall be able to finish without interruptions, even when app isn't in the foreground. How many files do you expect to sync that way? What's your phone model?

Thanks for your answer! My phone is a Fairphone 4 I am going to check on battery optimizations, try again to sync without any open apps and report back to you!

So the sync never worked at any time (I installed the app a few hours ago) and returned an error the first time I tried set it up Battery optimizations seem to be disabled. There is no orange icon and I think I clicked on it earlier Right now, I'm deleting the previous sync configuration I set up and creating another.

I am trying to sync a specific subfolder from my remote to a location on my phone (two-way mode)
sync frequency is set to 8 hours
enabled constraints are wifi only and only if battery not low

when clicking Save, it seems to be loading for a couple of minutes, then displays an error (Last error: Two-way sync failed. Try retrying using 'Force resync' button. Contact support for more information.) and logs look the same as what I posted earlier. S3Drive was the only application on the foreground the whole time The remote subfolder contains 42 files that amount for 6.8Mb

If it can help, I tried setting a similar 2-way sync with a remote folder from my Nextcloud server and I am encountering the exact same issue, so it doesn't seem to be tied to Proton specifically It can be worth noting that even though it is displaying an error, it does kind of work. On initial sync attempt, everything is being downloaded in the local directory. If I create a file within the local directory, it is being synced, but if I delete it from remote, it stays on local

Hi @Novembre, we plan to release some integration improvements along with Rclone update next week. This may or may not address this issue, but it would be good to apply it first before we carry on with the troubleshooting.

Hi! Sweet! Thanks for letting me know! I will report back to you with updated info when the update is up then

Hey, I got the app updated two days ago. A progress bar appeared eventually among notifications (I didn't see it before I think) but it seemed to be running indefinitely (showing the same error in app). I deleted all past sync configurations and tried with a new (Nextcloud) one but it showed the same error as before

Thanks for your feedback. We still didn't have chance to investigate that issue properly. We will try to provide and unpdate once we get to this and hopefully find out something. If we don't get back to you within some time, please remind us. We're willing to address this issue, yet we're overworked with couple other items ATM.