diff --git a/server/mergin/sync/storages/disk.py b/server/mergin/sync/storages/disk.py
index f4cb34fc..80715ed6 100644
--- a/server/mergin/sync/storages/disk.py
+++ b/server/mergin/sync/storages/disk.py
@@ -114,7 +114,11 @@ def move_to_tmp(src, dest=None):
             else:
                 root = tempfile.gettempdir()
             temp_path = os.path.join(root, "delete-me-" + dest, os.path.basename(src))
-            os.renames(src, temp_path)
+            try:
+                os.renames(src, temp_path)
+            except OSError as rename_err:
+                logging.error(f"Failed to move {src} to tmp: {rename_err}")
+                return None
         else:
             raise
     return temp_path
diff --git a/server/mergin/tests/test_disk_utils.py b/server/mergin/tests/test_disk_utils.py
index dd485078..c9abd66f 100644
--- a/server/mergin/tests/test_disk_utils.py
+++ b/server/mergin/tests/test_disk_utils.py
@@ -2,10 +2,13 @@
 #
 # SPDX-License-Identifier: AGPL-3.0-only OR LicenseRef-MerginMaps-Commercial
 
+import errno
+import logging
 import os
 import tempfile
 import shutil
 import pytest
+from unittest.mock import patch
 from ..sync.storages.disk import copy_file, copy_dir, move_to_tmp
 from ..sync.utils import generate_checksum
 from . import test_project_dir
@@ -85,3 +88,22 @@ def test_failures():
             os.path.join(test_project_dir, "not_found"),
             os.path.join(tempfile.gettempdir(), "new_dir"),
         )
+
+
+def test_move_to_tmp_full_disk_on_fallback(app, tmp_path, caplog):
+    """Fallback rename on cross-device error logs error and returns None when disk is full."""
+    cross_device_err = OSError(errno.EXDEV, "Invalid cross-device link")
+    no_space_err = OSError(errno.ENOSPC, "No space left on device")
+
+    src = tmp_path / "test_file.gpkg"
+    src.touch()
+
+    with caplog.at_level(logging.ERROR), patch(
+        "mergin.sync.storages.disk.os.renames",
+        side_effect=[cross_device_err, no_space_err],
+    ):
+        result = move_to_tmp(str(src))
+
+    assert result is None
+    assert "Failed to move" in caplog.text
+    assert str(src) in caplog.text