Cloudflare·Fixdeployintermediate

Cloudflare Worker Returning 500 Error

Quick Answer

Missing D1 binding in wrangler.toml, unhandled exceptions, or missing environment secrets. Start with "Check worker logs" before making broader code changes.

You're in the right place if...

!500 Internal Server Error from Worker
!API returns blank error
!Works locally but fails on Cloudflare

Why this happens

Missing D1 binding in wrangler.toml, unhandled exceptions, or missing environment secrets.

Fix

Check worker logs

Use wrangler tail to see live logs:

# Check worker logs:
wrangler tail

# Common cause: D1 binding missing in wrangler.toml
[[d1_databases]]
binding = "DB"
database_name = "your-db"
database_id = "your-id"

# Run locally to test:
wrangler dev

Prevent this next time

Always test with wrangler dev before deploying. It catches binding errors locally.