Technic Launcher modpacks keep crashing

[GeckoG4ming]

I opened technic launcher and downloaded modpacks that i want to play. However for some reason when i finish loading the modpack when i click play, it crashes and sends me back to launcher. Sometimes when the modpack does load, i try to start a world or join a server and when i do, it crashes and sens me back to the launcher. Is there a fix for this? because i'm not sure whats causing it

(I've opened modpacks with other launchers and they work just fine so it must be to do with technic)

If it isn't a launcher issue, then what is the issue then?

I've gone to other posts with similar issues and seen admins just state it isn't a launcher issue and lock it with no explanation to what it could be.
It would at least be beneficial to explain what the issues could be, even if it isn't a launcher issue

Also i've tried many things outside the launcher that could fix the issue and there has been no fix so it has come down to most likely being a launcher issue
and if it isn't then i would please like an explanation as to why it isn't a launcher issue and what the issue could be

[Lord Ptolemy]

Not a launcher issue. Locked.