I'm getting an error where MobBountyReloaded is not able to detect accounts from CraftConomy3 through Vault. I'm not sure what information I would need to provide in order to further assist in solving this problem but if you let me know what you need I'm happy to provide it.

I would need an actual error log. If you've updated Vault but not CC3, you'll need to make sure you have the latest CC3.

"[MobBountyReloaded] does not have an economy account."

It occurs when the plugin tries to pass money to the player's that actually killed the mobs. Mind you the following was tried to troubleshoot the issue. I attempted to create a player economy account manually for that player, but CraftConomy said that account already exists, which lead me to the conclusion that the hook problem is Vault.

CC3 and Vault are on latest versions recommended.

@JumanjiCraft - uhm, that doesn't look like an error from your console. I'll need the actual startup log that shows what is happening when Vault loads. If it finds CC3 just fine, then you'll need to get MobBounty to fix something.