CheckpointStateNotFoundError
langgraph.errors.CheckpointStateNotFoundError
Stack trace
langgraph.errors.CheckpointStateNotFoundError: Checkpoint state not found at path '/path/to/checkpoint/state'
File "/usr/local/lib/python3.9/site-packages/langgraph/memory.py", line 142, in load_checkpoint
raise CheckpointStateNotFoundError(f"Checkpoint state not found at path '{path}'")
File "/app/main.py", line 58, in main
memory.load_checkpoint(checkpoint_path) # triggers error
Why it happens
LangGraph requires a checkpoint state file to restore AI memory or graph state. This error occurs when the checkpoint file path is incorrect, missing, or the file was deleted or corrupted. Without this state, LangGraph cannot resume prior memory context.
Detection
Check for the existence of the checkpoint file path before loading. Log errors when the checkpoint path is missing or inaccessible to catch this early.
Causes & fixes
Checkpoint file path is incorrect or misspelled in the code or config
Verify and correct the checkpoint file path string to point to the valid existing checkpoint file location.
Checkpoint file was deleted or moved after initial creation
Restore the checkpoint file from backup or recreate the checkpoint by rerunning the memory initialization process.
Insufficient file system permissions prevent reading the checkpoint file
Ensure the running process has read permissions on the checkpoint directory and file.
Checkpoint file is corrupted or incomplete
Delete the corrupted checkpoint and create a fresh checkpoint state to avoid loading errors.
Code: broken vs fixed
from langgraph.memory import Memory
memory = Memory()
checkpoint_path = '/wrong/path/checkpoint_state.json'
memory.load_checkpoint(checkpoint_path) # triggers CheckpointStateNotFoundErrorimport os
from langgraph.memory import Memory
memory = Memory()
checkpoint_path = os.environ.get('LANGGRAPH_CHECKPOINT_PATH', '/correct/path/checkpoint_state.json')
memory.load_checkpoint(checkpoint_path) # fixed: correct path from env variable
print('Checkpoint loaded successfully')Workaround
Wrap load_checkpoint() in try/except CheckpointStateNotFoundError and initialize a new empty memory state if loading fails.
Prevention
Implement checkpoint path validation and existence checks before loading, and automate checkpoint backups to avoid missing state files.