I'm also getting an error 500 when trying to buy CSC.

I get to the purchase CSC page on https://kumos.subeta.net/cash-shop/credits

but when clicking any of the options 500 CSC to 12,500 CSC I get a "500 SERVER ERROR PAGE".

I've cleared everything and tried brand new devices with the same error :(.

I'm also getting tje same error and I'm unable to purchase csc using PayPal. It just keeps loading in the cash shop

this is an ongoing issue for a few months now apparently. Paypal dgaf so if you want CSC you have to use some other method. I haven't been able to buy any either

It won't take it through PayPal, but I can use stripe. I hope they fix the issue with buying it through PayPal.