I had to add debug var_dump to get curl error and fix it.

If you get empty string and no goal tracked in your analytics, you can try to debug it by doing this:

Modify the doTrackGoal method after the curl_exec call: var_dump(curl_error($ch)); to dump the cURL error.

Hope it could help.

Tracking works for us, but if it suddenly stopped working we need to be able to see this. Checking for GIF or empty result is not a convincing way to do this.

@olleharstedt @kylekatarnls
Not sure when tracking a goal would fail? You mean if you set an idGoal and the idGoal did not exist?

We could possibly return an HTTP 400 here https://github.com/matomo-org/matomo/blob/3.13.0/plugins/Goals/Tracker/GoalsRequestProcessor.php#L87-L92

Throwing an invalid param exception should do the trick

400 is one way, returning JSON with error message and error code another.

Nice!