When trying to join a parkour (Newly made, I dont have a previously made one to test with although I have used the plugin before and it has worked) I get an internal error message. It also fails when using a sign with no error message. No errors appear in the server command prompt.

Hi, Parkour doesn't officially support 1.13 just yet, but it will be coming eventually.
For now there will be one more release as v4.8 with a few nice features and fixes, then I will be creating Parkour v5.0 which will be to support 1.13 and I hope to support all the currently supported older versions.
If you want to join the Discord server, I post announcements on progress on there.

I'm closing this ticket as support for 1.13 has now been introduced and no problems should arise when joining the server now.