From 8665f299984de91850722c59075e9710220b765f Mon Sep 17 00:00:00 2001
From: David Stansby <dstansby@gmail.com>
Date: Fri, 16 May 2025 18:06:32 +0100
Subject: [PATCH 1/4] Add a GroupNotFoundError

---
 src/zarr/api/asynchronous.py |  4 ++--
 src/zarr/errors.py           | 10 +++++++++-
 2 files changed, 11 insertions(+), 3 deletions(-)

diff --git a/src/zarr/api/asynchronous.py b/src/zarr/api/asynchronous.py
index 4f3c9c3f8f..8445d18d6b 100644
--- a/src/zarr/api/asynchronous.py
+++ b/src/zarr/api/asynchronous.py
@@ -39,7 +39,7 @@
 )
 from zarr.core.metadata import ArrayMetadataDict, ArrayV2Metadata, ArrayV3Metadata
 from zarr.core.metadata.v2 import _default_compressor, _default_filters
-from zarr.errors import NodeTypeValidationError
+from zarr.errors import GroupNotFoundError, NodeTypeValidationError
 from zarr.storage._common import make_store_path
 
 if TYPE_CHECKING:
@@ -836,7 +836,7 @@ async def open_group(
             overwrite=overwrite,
             attributes=attributes,
         )
-    raise FileNotFoundError(f"Unable to find group: {store_path}")
+    raise GroupNotFoundError(store, store_path.path)
 
 
 async def create(
diff --git a/src/zarr/errors.py b/src/zarr/errors.py
index 441cdab9a3..31071fff81 100644
--- a/src/zarr/errors.py
+++ b/src/zarr/errors.py
@@ -10,7 +10,7 @@
 ]
 
 
-class BaseZarrError(ValueError):
+class BaseZarrError(Exception):
     """
     Base error which all zarr errors are sub-classed from.
     """
@@ -21,6 +21,14 @@ def __init__(self, *args: Any) -> None:
         super().__init__(self._msg.format(*args))
 
 
+class GroupNotFoundError(BaseZarrError, FileNotFoundError):
+    """
+    Raised when a group isn't found at a certain path.
+    """
+
+    _msg = "No group found in store {!r} at path {!r}"
+
+
 class ContainsGroupError(BaseZarrError):
     """Raised when a group already exists at a certain path."""
 

From ac1c82d3689d0ad475cfe7f1e1b924a6c5e90053 Mon Sep 17 00:00:00 2001
From: David Stansby <dstansby@gmail.com>
Date: Wed, 21 May 2025 12:39:14 +0100
Subject: [PATCH 2/4] Fixup tests

---
 tests/test_metadata/test_v3.py | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/tests/test_metadata/test_v3.py b/tests/test_metadata/test_v3.py
index a47cbf43bb..13549b10a4 100644
--- a/tests/test_metadata/test_v3.py
+++ b/tests/test_metadata/test_v3.py
@@ -20,7 +20,7 @@
     parse_fill_value,
     parse_zarr_format,
 )
-from zarr.errors import MetadataValidationError
+from zarr.errors import MetadataValidationError, NodeTypeValidationError
 
 if TYPE_CHECKING:
     from collections.abc import Sequence
@@ -62,7 +62,8 @@
 @pytest.mark.parametrize("data", [None, 1, 2, 4, 5, "3"])
 def test_parse_zarr_format_invalid(data: Any) -> None:
     with pytest.raises(
-        ValueError, match=f"Invalid value for 'zarr_format'. Expected '3'. Got '{data}'."
+        MetadataValidationError,
+        match=f"Invalid value for 'zarr_format'. Expected '3'. Got '{data}'.",
     ):
         parse_zarr_format(data)
 
@@ -88,7 +89,8 @@ def test_parse_node_type_invalid(node_type: Any) -> None:
 @pytest.mark.parametrize("data", [None, "group"])
 def test_parse_node_type_array_invalid(data: Any) -> None:
     with pytest.raises(
-        ValueError, match=f"Invalid value for 'node_type'. Expected 'array'. Got '{data}'."
+        NodeTypeValidationError,
+        match=f"Invalid value for 'node_type'. Expected 'array'. Got '{data}'.",
     ):
         parse_node_type_array(data)
 

From fedf099e0fcc8f8e8cc308bd026f9f21ff3280fe Mon Sep 17 00:00:00 2001
From: David Stansby <dstansby@gmail.com>
Date: Wed, 21 May 2025 12:40:35 +0100
Subject: [PATCH 3/4] Add changelog entries

---
 changes/3066.bugfix.rst  | 2 ++
 changes/3066.feature.rst | 1 +
 2 files changed, 3 insertions(+)
 create mode 100644 changes/3066.bugfix.rst
 create mode 100644 changes/3066.feature.rst

diff --git a/changes/3066.bugfix.rst b/changes/3066.bugfix.rst
new file mode 100644
index 0000000000..5499358f14
--- /dev/null
+++ b/changes/3066.bugfix.rst
@@ -0,0 +1,2 @@
+`~zarr.errors.BaseZarrError` now inherits from `Exception` instead of `ValueError`.
+This fix also affects all other exceptions in `zarr.errors`.
diff --git a/changes/3066.feature.rst b/changes/3066.feature.rst
new file mode 100644
index 0000000000..89d5ddb1c6
--- /dev/null
+++ b/changes/3066.feature.rst
@@ -0,0 +1 @@
+Added `~zarr.errors.GroupNotFoundError`, which is raised when attempting to open a group that does not exist.

From d1159559f2e3326fa99e696cbda899c382640aee Mon Sep 17 00:00:00 2001
From: David Stansby <dstansby@gmail.com>
Date: Sun, 25 May 2025 10:42:12 +0100
Subject: [PATCH 4/4] Remove inheritance change

---
 changes/3066.bugfix.rst | 2 --
 src/zarr/errors.py      | 2 +-
 2 files changed, 1 insertion(+), 3 deletions(-)
 delete mode 100644 changes/3066.bugfix.rst

diff --git a/changes/3066.bugfix.rst b/changes/3066.bugfix.rst
deleted file mode 100644
index 5499358f14..0000000000
--- a/changes/3066.bugfix.rst
+++ /dev/null
@@ -1,2 +0,0 @@
-`~zarr.errors.BaseZarrError` now inherits from `Exception` instead of `ValueError`.
-This fix also affects all other exceptions in `zarr.errors`.
diff --git a/src/zarr/errors.py b/src/zarr/errors.py
index 31071fff81..4d3140a4a9 100644
--- a/src/zarr/errors.py
+++ b/src/zarr/errors.py
@@ -10,7 +10,7 @@
 ]
 
 
-class BaseZarrError(Exception):
+class BaseZarrError(ValueError):
     """
     Base error which all zarr errors are sub-classed from.
     """