# X_ERROR_REPORTER_DSN_INVALID

## Means

the error monitor DSN is malformed

## Typical cause

`SENTRY_DSN` is not a URL, carries no public key, names no project, or uses a scheme that is not `http`/`https`. Thrown at boot rather than at the first failure, because a monitor that was never connected looks exactly like an app that never failed

## Fix

set `SENTRY_DSN=https://<publicKey>@<host>/<projectId>` in `.env`, then run `x env check`

[Core and runtime](/error-codes#core-and-runtime)