Unable to synchronize: cryptic "duplicate key" error

[glenux]

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Bug description

Since a few weeks, NextCloud Notes is unable to synchronize with my Nextcloud instance.

It fails with the "synchronization error message". The explanation is useless to find which note name should be fixed.

To Reproduce

The bug occured after I created a huge amount of notes, both from the smartphone and computer (around ~3000 notes), but i think creating a few notes both on smartphone & nextcloud instance should suffice.

The important thing is use similar titles to deliberately create name conflicts.

The note names were either normal text (for those created from the nextcloud instance, or from vim) and markdown links syntax for the notes created from "Share to... New note" in Android

Expected behavior

Nextcloud Notes should either :

• display an error message explaining which notes are conflicting on either sides
• rename the notes before downloading/uploading them

Screenshots

Smartphone:

OS Version: 4.4.111-15668094(G950FXXU4DSCB)
OS API Level: 28
Device: dreamlte
Manufacturer: samsung
Model (and Product): SM-G950F (dreamltexx)

Nextcloud Notes App

• App Version: 3.4.11
• App Version Code: 3004011
• App Flavor: fdroid

Server

• Files App Version Code: 30160190

Stacktrace

---

java.lang.IllegalStateException: Duplicate key 2505
	at j$.util.stream.-$$Lambda$Collectors$JCCUtBO-OYI_1WWo2UbajAktswI.apply(lambda:2)
	at j$.util.Map$-CC.$default$merge(Map.java:4)
	at j$.util.Map$-EL.merge(Map.java:9)
	at j$.util.stream.-$$Lambda$Collectors$vfQF-JJDCen_YKtRfgvkyywVMHc.accept(lambda:4)
	at j$.util.stream.ReduceOps$3ReducingSink.accept(ReduceOps.java:1)
	at j$.util.Iterator$-CC.$default$forEachRemaining(Iterator.java:3)
	at j$.util.Spliterators$IteratorSpliterator.forEachRemaining(Spliterators.java:5)
	at j$.util.stream.AbstractPipeline.copyInto(AbstractPipeline.java:6)
	at j$.util.stream.ReduceOps$ReduceOp.evaluateSequential(ReduceOps.java:3)
	at j$.util.stream.AbstractPipeline.evaluate(AbstractPipeline.java:5)
	at j$.util.stream.ReferencePipeline.collect(ReferencePipeline.java:17)
	at it.niedermann.owncloud.notes.persistence.NotesRepository.getIdMap(NotesRepository.java:428)
	at it.niedermann.owncloud.notes.persistence.NotesServerSyncTask.pullRemoteChanges(NotesServerSyncTask.java:208)
	at it.niedermann.owncloud.notes.persistence.NotesServerSyncTask.run(NotesServerSyncTask.java:96)
	at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:459)
	at java.util.concurrent.FutureTask.run(FutureTask.java:266)
	at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1167)
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:641)
	at java.lang.Thread.run(Thread.java:764)

[stefan-niedermann]

Dear @glenux

thanks for the detailed bug report.

display an error message explaining which notes are conflicting on either sides
rename the notes before downloading/uploading them

Renaming of the notes before down/uploading already happens. In your case there are not conflicts between client and server though, but within the Android app due to a bug of previous versions.
I just wrote a description about this error, please follow the instructions there.

Since you have a large amount of notes, please note that the initial sync might fail with a timeout. To prevent this, i recommend you to move the Notes to another folder and put them back step by step and synchronize between doing so.

Sorry for the inconveniences and good luck - just comment here if further trouble occur.