TypeError when clicking on a version in Changes viewer (history)

[RastoHu]

Description

Opening the Changes viewer (history) for a project and clicking on a specific version throws a TypeError: 'sqlite3.Cursor' object does not support the context manager protocol. This issue is not project-specific — it was reproduced on other projects.

Environment
[x] Staging [ ] PROD

Application (+ app version, build, operating system)

• QGIS 3.44.7-Solothurn
• Mergin Maps Plugin build: d-137311
• macOS Tahoe 26.3
• Also reproduced on: QGIS 3.40.15-Bratislava, Windows 11 64-bit ARM

Steps to reproduce

1. Open the Mergin Maps plugin in QGIS
2. Open the Changes viewer (history) for project tester-ws-1 / v2push_exploratory
3. Click on version v125

Actual results

Error is shown: TypeError: 'sqlite3.Cursor' object does not support the context manager protocol

Expected results

The selected version diff/changes should be displayed without error.

Screenshots or logs

An error has occurred while executing Python code:

TypeError: 'sqlite3.Cursor' object does not support the context manager protocol
Traceback (most recent call last):
  File "/Users/rastoh/Library/Application Support/QGIS/QGIS3/profiles/Rasto Lutra/python/plugins/Mergin/version_viewer_dialog.py", line 587, in selected_version_changed
    self.show_version_changes(version)
  File "/Users/rastoh/Library/Application Support/QGIS/QGIS3/profiles/Rasto Lutra/python/plugins/Mergin/version_viewer_dialog.py", line 674, in show_version_changes
    layers = make_version_changes_layers(QgsProject.instance().homePath(), version)
             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/Users/rastoh/Library/Application Support/QGIS/QGIS3/profiles/Rasto Lutra/python/plugins/Mergin/diff.py", line 406, in make_version_changes_layers
    features = diff_table_to_features(diff[table_name], db_schema[table_name], fields, cols_to_fields, db_conn)
               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/Users/rastoh/Library/Application Support/QGIS/QGIS3/profiles/Rasto Lutra/python/plugins/Mergin/diff.py", line 237, in diff_table_to_features
    db_row = get_row_from_db(db_conn, schema_table, entry_changes)
             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/Users/rastoh/Library/Application Support/QGIS/QGIS3/profiles/Rasto Lutra/python/plugins/Mergin/diff.py", line 78, in get_row_from_db
    with db_conn.cursor() as c:
         ^^^^^^^^^^^^^^^^
TypeError: 'sqlite3.Cursor' object does not support the context manager protocol


Python version: 3.12.11 (main, Dec 18 2025, 07:47:48) [Clang 16.0.0 (clang-1600.0.26.6)]
QGIS version: 3.44.7-Solothurn Solothurn, 4edb1325

Python Path:
/Applications/QGIS.app/Contents/Resources/qgis/python
/Users/rastoh/Library/Application Support/QGIS/QGIS3/profiles/Rasto Lutra/python
/Users/rastoh/Library/Application Support/QGIS/QGIS3/profiles/Rasto Lutra/python/plugins
/Applications/QGIS.app/Contents/Resources/qgis/python/plugins
/Applications/QGIS.app/Contents/Frameworks/lib/python312.zip
/Applications/QGIS.app/Contents/Frameworks/lib/python3.12
/Applications/QGIS.app/Contents/Frameworks/lib/python3.12/lib-dynload
/Applications/QGIS.app/Contents/Frameworks/lib/python3.12/site-packages
/Users/rastoh/Library/Application Support/QGIS/QGIS3/profiles/Rasto Lutra/python
.
/Users/rastoh/Documents/1_Projects/SSO_plugin_regression/v2push_exploratory

Conclusion
Created by Claude and supervised by a human test analyst.