We tested on Tor and it worked, but now we could replicate the issue with i2p. Some time ago we introduced a cookie that would force connections to be routed through https (with cryptography) instead of http, so I imagine this cookie was causing this error. Now we removed it. Can you check if now it's working? We came to the conclusion that this cookie was not needed because we have other code that automatically route connections to https when that's available.