Understanding AWS Lambda and Its Purpose

AWS Lambda is a serverless compute service that allows you to run code without provisioning or managing servers. It automatically scales your application by running code in response to triggers such as changes in data, shifts in system state, or user actions. Lambda functions can be configured to handle various workloads, including those requiring consistent performance through provisioned concurrency.

Recognizing the Symptom: ProvisionedConcurrencyConfigNotFoundException

When working with AWS Lambda, you might encounter the ProvisionedConcurrencyConfigNotFoundException. This error typically arises when attempting to invoke a Lambda function that is expected to have provisioned concurrency, but the configuration is missing or incorrectly set up.

What You Observe

Developers often notice this exception during function invocation or when attempting to update the function's concurrency settings. The error message indicates that the specified provisioned concurrency configuration does not exist.

Delving Into the Issue: ProvisionedConcurrencyConfigNotFoundException

The ProvisionedConcurrencyConfigNotFoundException occurs when AWS Lambda cannot find the provisioned concurrency configuration for the specified function version or alias. This can happen if the configuration was never set up, was deleted, or if there is a mismatch in the specified version or alias.

Common Causes

• The provisioned concurrency configuration was not created for the function version or alias.
• The configuration was accidentally deleted or modified.
• Incorrect version or alias specified in the request.

Steps to Fix the ProvisionedConcurrencyConfigNotFoundException

To resolve this issue, follow these steps to ensure that the provisioned concurrency configuration is correctly set up and associated with the correct function version or alias.

Step 1: Verify the Function Version or Alias

Ensure that you are specifying the correct function version or alias when configuring or invoking the Lambda function. You can list all versions and aliases using the AWS CLI:

aws lambda list-versions-by-function --function-name aws lambda list-aliases --function-name

Step 2: Check Existing Provisioned Concurrency Configurations

Use the AWS CLI to check if a provisioned concurrency configuration exists for the specified version or alias:

aws lambda get-provisioned-concurrency-config --function-name --qualifier

If no configuration is found, you will need to create one.

Step 3: Create or Update the Provisioned Concurrency Configuration

If the configuration is missing, create it using the following command:

aws lambda put-provisioned-concurrency-config --function-name --qualifier --provisioned-concurrent-executions

Replace <desired-count> with the number of concurrent executions you want to provision.

Additional Resources

For more detailed information on managing provisioned concurrency, refer to the AWS Lambda Documentation. If you continue to experience issues, consider reaching out to AWS Support for further assistance.