I can’t seem to use lvl 70 boosts on any of my characters. I recently came back to the game after a while and noticed I have 3 lvl 70 boosters to use, but whenever I select a character I get a “Internal Error” message and nothing happens. I really don’t want to have to lvl 4 characters all the way to 80.
This is the Blizzard support article
https://us.support.blizzard.com/en/help/article/10411
* Can’t boost my character, I receive “Internal Error”
If you recently applied another character service to your character (like a transfer or faction change), you must wait 72 hours before you can use a boost on the same character.
If you just purchased the boost or expansion upgrade, you must wait until the payment is fully processed. This should take no more than 24 hours. You can keep track of the status of your order in your [Transaction History]
(https://account.blizzard.com/transactions).
Doesn’t sound like that applies to you.
Something to do with the Warband screen? Try logging into the character you want to boost, logging out, and then applying the boost?