ERROR We are unable to process your request. An unknown error occurred.

Here's How I Solved It:

Add a Payment Method
    Go to account.apple.com and add a payment method that matches the country/region you’re using.

Update Phone Number
    Change your phone number everywhere (address, payment, 2FA) to one from the country/region where you want to create the developer account.

Same issue , what reason i dont know, apple doesn't need to say the reason???!

We are unable to process your request. An unknown error occurred.

my apple team hello i need to payment to you for get developer account , iam safety and good boy iam not bad boy i need to pay so why this error

We are unable to process your request. An unknown error occurred.

:)

Same issue , what reason i dont know, apple doesn't need to say the reason???!

We are unable to process your request. An unknown error occurred.

my apple team hello i need to payment to you for get developer account , iam safety and good boy iam not bad boy i need to pay so why this error

We are unable to process your request. An unknown error occurred.

:)

Any solution? I have valid phone number and valid credit card and i have got google play in one minute without complicated issue

hello apple can fix the issue or tell me the reason to fix it

https://www.reddit.com/r/iOSProgramming/comments/17974ry/apple_developer_enroll_error/?sort=new

See the reply in the above Redddit thread You just need to add the two factor authentication as you current locations developer acccount as mentioned in there and it works.

"The trusted phone number for 2FA has to be the same region as the Apple ID you try to enroll"

Hope this helps

Having the same issue.