Sync loop path to diff files in .mergin folder exceeds 260 characters

User encountered an issue where they synced their project and the plugin entered a sync loop that created 100s of versions of the project within a few minutes without the user realising what had happened.

This appears to have been triggered by the project being stored in a directory with a long file path. Though the project directory and files were within the 260 character limit for Windows, some of the diff files in the .mergin folder exceeded this limit. The missing diff file causes the plugin to fail to create a changeset and the plugin continues to re-sync, creating new project versions, until the user kills the app.

This is related to ticket (Lutra internal use only): https://odoo.lutraconsulting.co.uk/odoo/helpdesk.ticket/helpdesk.ticket/16516

@wonder-sk

@wonder-sk let's discuss fix approach.

@wonder-sk

@wonder-sk will check the geodiff implementation. Python looks like it's safe to handle longer paths from 3.6 version - s we do not need any proxy fs.py in py-client code itself.

@harminius - would you like double check if everyting in py client is fine with longer paths when you revert fs.py in PR implementation?

Pending geodiff ticket: MerginMaps/geodiff#264

@MarcelGeo

@wonder-sk will check the geodiff implementation. Python looks like it's safe to handle longer paths from 3.6 version - s we do not need any proxy fs.py in py-client code itself.

@harminius - would you like double check if everyting in py client is fine with longer paths when you revert fs.py in PR implementation?

@MarcelGeo I tested long path files manipulation in python console and qgis bundled python (3.12) failed to access unprefixed paths

QGIS embedded Python long-path test
Python: 3.12.11 (main, Jun 17 2025, 13:41:12) [MSC v.1943 64 bit (AMD64)]
Host executable: C:\OSGeo4W\bin\qgis-ltr-qt6-bin.exe
RtlAreLongPathsEnabled() for this process: True
LongPathsEnabled registry value: 1

Target directory length: 284
Target directory: C:\Users\ACER\qgis_longpath_test\aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa0\aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa1\aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa2\aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa3\aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa4\aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa5

--- os.makedirs WITHOUT prefix ---
[FAIL] makedirs(deep) : FileNotFoundError [WinError 3] Systém nemůže nalézt uvedenou cestu: 'C:\\Users\\ACER\\qgis_longpath_test\\aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa0\\aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa1\\aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa2\\aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa3\\aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa4\\aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa5'

--- os.makedirs WITH prefix ---
[OK]   makedirs(lp(deep)) 

Target file path length: 318

--- open() WITHOUT prefix ---
[FAIL] open(target, 'w') : FileNotFoundError [Errno 2] No such file or directory: 'C:\\Users\\ACER\\qgis_longpath_test\\aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa0\\aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa1\\aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa2\\aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa3\\aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa4\\aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa5\\test_file_data.gpkg-diff-someuuid'

--- open() WITH prefix ---
[OK]   open(lp(target), 'w') -> 17

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Sync loop path to diff files in .mergin folder exceeds 260 characters #932

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Sync loop path to diff files in .mergin folder exceeds 260 characters #932

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MarcelGeo commented on Aug 28, 2026

MarcelGeo commented on Sep 2, 2026

wonder-sk commented on Sep 4, 2026

harminius commented on Sep 4, 2026

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