Files saved to Nextcloud via Android "Save as" (DocumentsProvider) are created with 0 bytes since 34.0.1 #17269

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• 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".
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Steps to reproduce

1. In a third-party app (e.g. Shelly), choose Export → "Save as" and pick Nextcloud as the storage location (via Android's Storage Access Framework / DocumentsProvider).
2. Save the file into any Nextcloud folder.
3. Open the file on the server: it exists but is 0 bytes / empty.

Expected behaviour

The file is uploaded with its real content / correct size.

Actual behaviour

The file is created on the server but stays 0 KB (empty). The source app reports "Cannot save document".

Saving the same file to local Downloads works, and a direct upload from within the Nextcloud app also produces the correct file size — so only the "Save as" / DocumentsProvider path is
broken. It affects any target folder (own folders too, not only shares). Quota and free space were ruled out (server 17% free, no maintenance mode).

Regression: worked in early June (app 34.0.0, released 2026-06-08); first failure after the app update of 2026-06-24 (34.0.1). Resembles the old #6726 (closed, 2020).

Android version

16

Device brand and model

Samsung Galaxy S24

Stock or custom OS?

Stock

Nextcloud android app version

34.0.1

Nextcloud server version

34.0.1

Using a reverse proxy?

No

Android logs

No response

Server error logs

Additional information

No app logs captured (stable build, no easy logcat access). Reproducible on every attempt via the "Save as" dialog. The file is created as a 0-byte placeholder every time; only uploads
through the app's own upload UI work correctly.