Access denied error 0x5

[Yebeka]

I just wanted to play Terraria but Steam says access denied error 0x5 out of nowhere, then it tells me that Terraria.exe doesn't exist. I've tried reinstalling Steam, rebooted my pc a bunch of times, opening Steam as an admin etc, nothing works. Does anyone know how to fix that?

[SomeGuy712x]

I just had that same error when I tried to install and play a couple games last night (Helen's Mysterious Castle and Neptunia Shooter, both suggested to me by the Steam Spring Cleaning event). After trying a few things myself, someone suggested that I restart my computer, so I did that, and after the computer was done rebooting, both of those games started up just fine for me.

But, since you said you rebooted your PC a bunch of times, and it still didn't work, I guess your situation isn't the exact same as mine. So, I have no idea.

EDIT: Wait, what? Now Helen's Mysterious Castle and Neptunia Shooter are giving me the same "Access is denied." 0x5 error again. But, they were working just fine after my reboot last night, so what's the actual cause of this error then, and how can it be fixed?

ANOTHER EDIT: Oh, turns out it was my firewall getting in the way somehow. I wish I'd checked that earlier.