missing chunkmanager: update error message

xarray/namedarray/parallelcompat.py

@@ -115,7 +115,8 @@ def guess_chunkmanager(
     if isinstance(manager, str):
         if manager not in chunkmanagers:
             raise ValueError(
-                f"unrecognized chunk manager {manager} - must be one of: {list(chunkmanagers)}"
+                f"requested chunk manager '{manager}' not found in available chunk managers"
+                f"({list(chunkmanagers)}) - do you need to install '{manager}'?"
             )
 
         return chunkmanagers[manager]

xarray/tests/test_parallelcompat.py

@@ -153,7 +153,7 @@ def test_get_chunkmanger(self, register_dummy_chunkmanager) -> None:
         assert isinstance(chunkmanager, DummyChunkManager)
 
     def test_fail_on_nonexistent_chunkmanager(self) -> None:
-        with pytest.raises(ValueError, match="unrecognized chunk manager foo"):
+        with pytest.raises(ValueError, match="requested chunk manager 'foo' not found"):
             guess_chunkmanager("foo")
 
     @requires_dask
@@ -163,7 +163,9 @@ def test_get_dask_if_installed(self) -> None:
 
     @pytest.mark.skipif(has_dask, reason="requires dask not to be installed")
     def test_dont_get_dask_if_not_installed(self) -> None:
-        with pytest.raises(ValueError, match="unrecognized chunk manager dask"):
+        with pytest.raises(
+            ValueError, match="requested chunk manager 'dask' not found"
+        ):
             guess_chunkmanager("dask")
 
     @requires_dask