Actually, the problem was in functions.php, from some reason it has a problem with line break after php tag.

Marked as resolved

This kind of issue is usually caused by either conflict with other plugins or the active theme.

Please deactivate the plugins/theme one by one and check after each deactivation to find the problem maker.

Keep the cache plugin (if you have) deactivated during this testing process.

Don't forget to press Ctrl+F5(twice) on the frontend each time before checking.

During development with wpdiscuz, after deployment i am having some troubles when commenting.

Attaching the photo of the error, pretty weird and when i comment, if i refresh the page the comment is shown correctly and with no errors.

Appreciate your help, 

Ben