From c08b3bbb38f865fbd6747fe11695b5aa949eaa04 Mon Sep 17 00:00:00 2001
From: Vecko <36369090+VeckoTheGecko@users.noreply.github.com>
Date: Wed, 24 Jun 2026 16:02:11 +0200
Subject: [PATCH 1/2] Update error message in ParticleFile writing

---
 src/parcels/_core/particlefile.py | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/src/parcels/_core/particlefile.py b/src/parcels/_core/particlefile.py
index 7a3fc9d64..0c9173bdf 100644
--- a/src/parcels/_core/particlefile.py
+++ b/src/parcels/_core/particlefile.py
@@ -106,11 +106,13 @@ def __init__(
 
         if path.exists():
             if mode is None:
-                raise ValueError(f"{path=!r} already exists. Use mode='w' or use a new path.")
+                msg = f"Path '{path}' already exists. Use mode='w' or use a new path."
+                raise ValueError(msg)
             if mode == "w":
                 path.unlink()
         if not path.parent.exists():
-            raise ValueError(f"Folder location for {path=!r} does not exist. Create the folder location first.")
+            msg = f"Folder location for '{path} does not exist. Create the folder location first."
+            raise ValueError(msg)
 
         self.metadata = {}
 

From 6a20d765594fd129a54a934a35bd3159b676c46b Mon Sep 17 00:00:00 2001
From: Vecko <36369090+VeckoTheGecko@users.noreply.github.com>
Date: Wed, 24 Jun 2026 16:28:46 +0200
Subject: [PATCH 2/2] Add test

---
 tests/test_particlefile.py | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/tests/test_particlefile.py b/tests/test_particlefile.py
index dc0e232c1..c98385d48 100755
--- a/tests/test_particlefile.py
+++ b/tests/test_particlefile.py
@@ -431,6 +431,18 @@ def test_particlefile_init_existing_path_modes(fieldset, tmp_parquet):
     assert len(df_first) == len(df_overwrite)
 
 
+def test_particlefile_init_existing_path_no_mode(tmp_parquet):
+    tmp_parquet.touch()
+    with pytest.raises(ValueError, match="already exists"):
+        ParticleFile(tmp_parquet, outputdt=np.timedelta64(1, "s"))
+
+
+def test_particlefile_init_nonexistent_parent(tmp_path):
+    path = tmp_path / "nonexistent_dir" / "file.parquet"
+    with pytest.raises(ValueError, match="does not exist"):
+        ParticleFile(path, outputdt=np.timedelta64(1, "s"))
+
+
 def test_particlefile_init_invalid_mode(tmp_parquet):
     with pytest.raises(ValueError, match="Invalid mode value"):
         ParticleFile(tmp_parquet, outputdt=np.timedelta64(1, "s"), mode="something-else")