diff --git a/m_flow/adapters/graph/get_graph_adapter.py b/m_flow/adapters/graph/get_graph_adapter.py
index 691b8ad..4aa560c 100644
--- a/m_flow/adapters/graph/get_graph_adapter.py
+++ b/m_flow/adapters/graph/get_graph_adapter.py
@@ -128,7 +128,7 @@ def _build_adapter(
         "neptune",
         "neptune_analytics",
     ]
-    raise EnvironmentError(f"Unknown graph provider '{graph_database_provider}'. Supported: {', '.join(known)}")
+    raise OSError(f"Unknown graph provider '{graph_database_provider}'. Supported: {', '.join(known)}")
 
 
 # ---------------------------------------------------------------------------
@@ -138,7 +138,7 @@ def _build_adapter(
 
 def _require(val: Optional[str], label: str) -> None:
     if not val:
-        raise EnvironmentError(f"Missing required configuration: {label}")
+        raise OSError(f"Missing required configuration: {label}")
 
 
 def _validate_prefix(url: str, prefix: str) -> None:
diff --git a/m_flow/adapters/vector/create_vector_engine.py b/m_flow/adapters/vector/create_vector_engine.py
index 4d38808..84af906 100644
--- a/m_flow/adapters/vector/create_vector_engine.py
+++ b/m_flow/adapters/vector/create_vector_engine.py
@@ -108,7 +108,7 @@ def create_vector_engine(
         "Pinecone",
         "Milvus",
     ]
-    raise EnvironmentError(f"Unknown vector provider: {vector_db_provider}. Supported: {', '.join(known)}")
+    raise OSError(f"Unknown vector provider: {vector_db_provider}. Supported: {', '.join(known)}")
 
 
 def _create_pgvector_adapter(embedder, api_key: str):
@@ -119,7 +119,7 @@ def _create_pgvector_adapter(embedder, api_key: str):
     required = [cfg.db_host, cfg.db_port, cfg.db_name, cfg.db_username, cfg.db_password]
 
     if not all(required):
-        raise EnvironmentError("Missing PGVector credentials")
+        raise OSError("Missing PGVector credentials")
 
     conn_str = f"postgresql+asyncpg://{cfg.db_username}:{cfg.db_password}@{cfg.db_host}:{cfg.db_port}/{cfg.db_name}"
 
@@ -151,7 +151,7 @@ def _create_neptune_adapter(url: str, embedder):
         raise ImportError("langchain_aws not installed. Run: pip install langchain_aws")
 
     if not url:
-        raise EnvironmentError("Neptune endpoint URL required")
+        raise OSError("Neptune endpoint URL required")
 
     from m_flow.adapters.hybrid.neptune_analytics.NeptuneAnalyticsAdapter import (
         NEPTUNE_ANALYTICS_ENDPOINT_URL,
diff --git a/m_flow/context_global_variables.py b/m_flow/context_global_variables.py
index 170d2d5..fa76162 100644
--- a/m_flow/context_global_variables.py
+++ b/m_flow/context_global_variables.py
@@ -51,10 +51,10 @@ def _require_handler_registered(
     kind: str,
     registry: dict,
 ) -> None:
-    """Raise ``EnvironmentError`` when *handler_name* is absent from *registry*."""
+    """Raise ``OSError`` when *handler_name* is absent from *registry*."""
     if handler_name in registry:
         return
-    raise EnvironmentError(
+    raise OSError(
         f"The {kind} dataset-database handler '{handler_name}' is not recognised. "
         f"Supported handlers: {list(registry)}. "
         f"Set {_ACL_ENV_KEY}=false to disable access-control mode."
@@ -71,7 +71,7 @@ def _require_handler_matches_provider(
     expected = registry[handler_name]["handler_provider"]
     if expected == provider:
         return
-    raise EnvironmentError(
+    raise OSError(
         f"Mismatch: the {kind} handler '{handler_name}' expects provider "
         f"'{expected}' but '{provider}' is configured. "
         f"Set {_ACL_ENV_KEY}=false to disable access-control mode."
diff --git a/m_flow/shared/files/utils/get_file_content_hash.py b/m_flow/shared/files/utils/get_file_content_hash.py
index a121f25..677fc1a 100644
--- a/m_flow/shared/files/utils/get_file_content_hash.py
+++ b/m_flow/shared/files/utils/get_file_content_hash.py
@@ -37,7 +37,7 @@ async def get_file_content_hash(source: Union[str, BinaryIO]) -> str:
             async with backend.open(name, "rb") as fh:
                 return _hex_digest_of(fh)
         return _hex_digest_of(source)
-    except IOError as err:
+    except OSError as err:
         raise FileContentHashingError(
             message=f"Hashing failed for {source!r}: {err}",
         ) from err