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Reserved environment variables

Last updated November 25, 2025

The following environment variable names are reserved and therefore unavailable for use:

  • AWS_SECRET_KEY
  • AWS_EXECUTION_ENV
  • AWS_LAMBDA_LOG_GROUP_NAME
  • AWS_LAMBDA_LOG_STREAM_NAME
  • AWS_LAMBDA_FUNCTION_NAME
  • AWS_LAMBDA_FUNCTION_MEMORY_SIZE
  • AWS_LAMBDA_FUNCTION_VERSION
  • NOW_REGION
  • TZ
  • LAMBDA_TASK_ROOT
  • LAMBDA_RUNTIME_DIR

Allowed environment variables

The following environment variable names are allowed by Vercel Vercel Function runtimes:

  • AWS_ACCESS_KEY_ID
  • AWS_SECRET_ACCESS_KEY
  • AWS_SESSION_TOKEN
  • AWS_REGION
  • AWS_DEFAULT_REGION

These variables may appear in your Vercel Functions even if you don't set them in your project explicitly. These values do not grant any AWS permissions and are not usable as AWS credentials. Configure your own AWS credentials using environment variables or set up OIDC.

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