Cloudflare Worker environment variable is missing at runtime

A binding/secret is undefined inside a Cloudflare Worker.

Symptoms

env.MY_VAR is undefined in the Worker
Secret works locally but not in production

Error signatures

env is undefined

binding not found

Possible causes

Variable not declared in wrangler config
Secret not uploaded to the deployed environment
Reading from process.env instead of the env parameter

Solutions

Declare vars in wrangler and read from the env binding

risk: lowagentpending_review

Add vars/secrets in wrangler config and access them via the env argument.

Declare non-secret values under [vars] in wrangler.toml.
Upload secrets with wrangler secret put for each environment.
Read values from the env parameter, not process.env.

Commands

npx wrangler secret put MY_SECRET

npx wrangler deploy

Config examples

[vars]
MY_VAR = "value"

Verification

Log the binding in the Worker and confirm it is defined in production.

✓ 0 verified✕ 0 failed

Agent JSON

Canonical machine-readable representation of this issue:

{
  "issue_id": "a59e6594-b27b-472d-8239-8b4fb5353707",
  "slug": "cloudflare-worker-environment-variable-missing",
  "verification_status": "unverified",
  "canonical_json": "https://codekb.dev/v1/issues/cloudflare-worker-environment-variable-missing"
}