Lambda Inactive state

Recently, I have got 500 HTTP response from my API Gateway endpoint integrated with lambda function. I found integration error in logs

Lambda invocation failed with status: 409. Lambda request id: f272af2a-2631-48b8-b0b2-3f5e1193a393
Execution failed due to configuration error: Lambda is initializing your function.It will be ready to invoke once your function state becomes ACTIV

It turned out that the Api gateway endpoint and lambda hadn’t been invoked for 20 day and SnapStart on PublishedVersions was turned on in my lambda configuration. As a result lambda went into Inactive state.

Inactive – The function version hasn't been invoked for 14 days. When the function version becomes Inactive, Lambda deletes the snapshot. If you invoke the function version after 14 days, Lambda returns a SnapStartNotReadyException response and begins initializing a new snapshot. Wait until the function version reaches the Active state, and then invoke it again.

After couple of seconds my Api gateway endpoint and lambda were working again.