diff --git a/libs/cli/langgraph_cli/cli.py b/libs/cli/langgraph_cli/cli.py
index 9c11c4b10..98d585f40 100644
--- a/libs/cli/langgraph_cli/cli.py
+++ b/libs/cli/langgraph_cli/cli.py
@@ -575,6 +575,13 @@ def dev(
     try:
         from langgraph_api.cli import run_server
     except ImportError:
+        py_version_msg = ""
+        if sys.version_info < (3, 11):
+            py_version_msg = (
+                "\n\nNote: The in-mem server requires Python 3.11 or higher to be installed."
+                f" You are currently using Python {sys.version_info.major}.{sys.version_info.minor}."
+                ' Please upgrade your Python version before installing "langgraph-cli[inmem]".'
+            )
         try:
             from importlib import util
 
@@ -582,16 +589,19 @@ def dev(
                 raise click.UsageError(
                     "Required package 'langgraph-api' is not installed.\n"
                     "Please install it with:\n\n"
-                    '    pip install -U "langgraph-cli[inmem]"\n\n'
+                    '    pip install -U "langgraph-cli[inmem]"'
+                    f"{py_version_msg}"
                 ) from None
         except ImportError:
             raise click.UsageError(
                 "Could not verify package installation. Please ensure Python is up to date and\n"
                 "langgraph-cli is installed with the 'inmem' extra: pip install -U \"langgraph-cli[inmem]\""
+                f"{py_version_msg}"
             ) from None
         raise click.UsageError(
             "Could not import run_server. This likely means your installation is incomplete.\n"
             "Please ensure langgraph-cli is installed with the 'inmem' extra: pip install -U \"langgraph-cli[inmem]\""
+            f"{py_version_msg}"
         ) from None
 
     config_json = langgraph_cli.config.validate_config_file(pathlib.Path(config))
diff --git a/libs/cli/pyproject.toml b/libs/cli/pyproject.toml
index 7e166ee25..6595cc7b9 100644
--- a/libs/cli/pyproject.toml
+++ b/libs/cli/pyproject.toml
@@ -1,6 +1,6 @@
 [tool.poetry]
 name = "langgraph-cli"
-version = "0.1.66"
+version = "0.1.67"
 description = "CLI for interacting with LangGraph API"
 authors = []
 license = "MIT"
diff --git a/libs/cli/tests/unit_tests/test_config.py b/libs/cli/tests/unit_tests/test_config.py
index 6bbc12aab..27aea10bd 100644
--- a/libs/cli/tests/unit_tests/test_config.py
+++ b/libs/cli/tests/unit_tests/test_config.py
@@ -91,10 +91,22 @@ def test_validate_config():
         validate_config({"python_version": "3.10"})
     assert "Minimum required version" in str(exc_info.value)
 
-    config = validate_config({"python_version": "3.11-bullseye", "dependencies": ["."], "graphs": {"agent": "./agent.py:graph"}})
+    config = validate_config(
+        {
+            "python_version": "3.11-bullseye",
+            "dependencies": ["."],
+            "graphs": {"agent": "./agent.py:graph"},
+        }
+    )
     assert config["python_version"] == "3.11-bullseye"
 
-    config = validate_config({"python_version": "3.12-slim", "dependencies": ["."], "graphs": {"agent": "./agent.py:graph"}})
+    config = validate_config(
+        {
+            "python_version": "3.12-slim",
+            "dependencies": ["."],
+            "graphs": {"agent": "./agent.py:graph"},
+        }
+    )
     assert config["python_version"] == "3.12-slim"