Passwords with special characters make the WebUI crash with an error 500

[Deses]

I was having problems with the WebUI whenever I used a password, and I realized the password is the problem.

The password jnS#8w\XXjrlL]=_r_4=\15:<8SW-2$v*K13FBe0 triggers the error.
A password with just letters and numbers like 60x7XR9MgyV4MZRfBCe8JJ962Oa3hEw6o3CDrZe3 doesn't produce the error 500.

The workers are still OK because I see my total amount uploaded slowly increase in the leaderboard, so just the WebUI is what breaks.