net::ERR_EMPTY_RESPONSE

In the console I’m getting a error. What does this mean?

Code:
mtc.js:6 OPTIONS https://mautic.goedboerenindestad.nl/mtc net::ERR_EMPTY_RESPONSE MauticJS.makeCORSRequest @ mtc.js:6 MauticJS.getTrackedContact @ mtc.js:62 (anonymous function) @ mtc.js:10

In the console I’m getting a error. What does this mean?

mtc.js:6 OPTIONS https://mautic.goedboerenindestad.nl/mtc net::ERR_EMPTY_RESPONSE MauticJS.makeCORSRequest @ mtc.js:6 MauticJS.getTrackedContact @ mtc.js:62 (anonymous function) @ mtc.js:10