How to Fix Network Error in Deno: Simple Steps

Network errors in deno often happen because the program lacks permission to access the network. Fix this by running your script with the --allow-net flag to grant network access.

Why This Happens

Deno is secure by default and blocks network access unless explicitly allowed. If you try to fetch data from the internet without permission, Deno throws a network error.

typescript

const response = await fetch('https://example.com');
const data = await response.text();
console.log(data);

Output

error: Uncaught PermissionDenied: network access to "https://example.com" is not allowed
    at fetch (<anonymous>:1:1)
    at file:///app/mod.ts:1:15

The Fix

Run your Deno script with the --allow-net flag to give it permission to access the network. This tells Deno it is safe to make network requests.

bash

deno run --allow-net mod.ts

Output

The script runs successfully and prints the fetched data from https://example.com

Prevention

Always specify the minimum permissions your Deno script needs. Use --allow-net=example.com to restrict network access to specific domains. This keeps your app secure and avoids unexpected network errors.

Use Deno's deno lint tool to catch permission issues early.

Related Errors

Other permission errors include:

• File system access denied: Fix by adding --allow-read or --allow-write.
• Environment variable access denied: Fix by adding --allow-env.

Key Takeaways

Deno blocks network access by default for security.

Use --allow-net flag to grant network permission when running scripts.

Limit network permissions to specific domains when possible.

Use deno lint to detect permission issues early.

Other permission errors require their own flags like --allow-read or --allow-env.