Auto Upload high CPU usage #17895

⚠️ Before posting ⚠️

• This is a bug, not a question or an enhancement.
• I've searched for similar issues and didn't find a duplicate.
• I've written a clear and descriptive title for this issue, not just "Bug" or "Crash".
• I agree to follow Nextcloud's Code of Conduct.

Steps to reproduce

Steps to reproduce
The issue is not deterministic, but occurs frequently:

Enable Auto Upload for the camera folder(s), configured to upload only while charging.

Connect the phone to a charger so Auto Upload starts.

After a variable amount of time, the phone suddenly becomes very hot.

CPU usage rises sharply. In addition to the Nextcloud app, system_server shows high CPU usage; sometimes, surfaceflinger, kswapd0, Samsung vendor/system processes, and com.google.android.ext.services are also affected.

Some uploads fail with a connection error to the Nextcloud server.

Despite the reported failure, the affected files are often uploaded successfully the following day.

Force-stopping the Nextcloud app stops the high CPU load. If the app has been running overnight, a reboot may be required.

The problem started around early April 2026.

Expected behaviour

Auto Upload should upload new files with moderate CPU, network and battery usage. Temporary connection errors should be retried in a controlled way, without causing sustained high CPU load, overheating, or excessive system_server activity.

Actual behaviour

While charging, Auto Upload can enter a state with very high CPU usage and severe device heating. system_server is heavily loaded as well. Uploads sometimes fail with connection errors, but are later uploaded successfully, suggesting either an aggressive retry loop or an upload-state/bookkeeping problem.

Force-stopping the app immediately reduces the load. After the app has run overnight, only a reboot reliably restores normal behaviour.

Android version

Android version: Android 17 / One UI 9.0

Device brand and model

Samsung Galaxy S25

Stock or custom OS?

Stock

Nextcloud android app version

35.0.1

Nextcloud server version

35.0.2

Using a reverse proxy?

Yes

Android logs

Normal logcat did not show a clear app-level error. Samsung extended app debugging was not enabled during previous occurrences.
I can provide:
A logcat capture during an occurrence
A Samsung bug report after enabling extended debugging

Server error logs

There were no relevant logs on the server.

Additional information

Two changes coincided with the first occurrence:

The Nextcloud database was moved to an external server to reduce SSD wear. The web UI is usable but slower; database latency could contribute to upload timeouts or retry loops.

Around the same time, Google Play permission problems affected the Nextcloud Android app. I reset the app, but did not completely uninstall and reinstall it.

The fact that failed uploads are successfully uploaded the next day makes me suspect that the app may repeatedly retry or rescan files after a network failure, possibly interacting badly with Android/Samsung background-process management.

Questions:

Is this related to the known high battery/CPU usage reports for Auto Upload? Similar reports exist for high battery drain with auto upload, repeated background activity, and upload loops with large folders.

Could an upload failure trigger an excessive retry loop?

Should I test the F-Droid build for better logs, enable Samsung extended debugging, or completely uninstall/reinstall the app?

Could the external database latency or the WireGuard/Apache proxy path contribute to the connection failures?
IPv4 path: homeserver → WireGuard tunnel → Apache 2 reverse proxy. IPv6 should connect directly to the homeserver.

Screenshot:

Independently of Auto Upload, when scrolling through the photo/media view, the server connection repeatedly drops after approximately 5 minutes. Initially, images load normally. Afterwards, only cached files can be accessed. This happens even when Auto Upload is not actively uploading.
It may indicate a network/request timeout, an IPv6/WireGuard/Apache proxy issue, or a problem in the app’s media browsing/request handling. The high CPU load may be a separate Auto Upload issue, but both started around the same time.