Issues serving Edge Functions locally

Last edited: 2/6/2026

If supabase functions serve fails or you're having trouble running Edge Functions locally, follow these steps to diagnose and resolve the issue.

Debugging steps#

Use debug mode#

Run the serve command with the --debug flag for detailed output:

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supabase functions serve your-function --debug

Check port availability#

Ensure the required ports are available. The Supabase CLI uses ports 54321 and 8081 by default:

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# Check if port 54321 is in use
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lsof -i :54321
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# Check if port 8081 is in use
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lsof -i :8081

If these ports are in use, stop the processes using them or configure different ports.

Common issues#

Port conflicts#

Another process may be using the required ports. Check for:

Other Supabase projects running locally
Docker containers
Other development servers

Deno cache issues#

Clear the Deno cache if you're experiencing module resolution problems:

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deno cache --reload /path/to/function/index.ts

Environment variables#

Make sure your .env file is properly configured and accessible to the CLI.

Getting more help#

If the problem persists, search the following repositories for similar error messages:

If the output from these commands does not help resolve the issue, open a support ticket via the Supabase Dashboard (by clicking the "Help" button at the top right) and include all output and details about your commands.