[Bug] Failed to deserialize a message - Failed to recover an affine group from an x-coordinate of

[vicsn]

🐛 Bug Report

We should not have such scary messages on the testnet validator: 2026-05-21 13:58:47.822 warn Failed to deserialize a message - Failed to recover an affine group from an x-coordinate of 4207180423372579853394536301168837222429115504538299627604263789037326389853field

It happens in Router, so it might just be a client that didn't upgrade

I've checked with a small test and got the same  error, i.e. the x coordinate not corresponding to a point in the large prime-order subgroup of the protocol curve. Without any more context of where this is happening it's hard to guess, but I can think of at least the following:

• The deserialiser thinks that it should expect a point (which we always de/serialise in the form of their x coordinate), but the serialiser put there a field element which does not come from a point (e.g. because they are looking at different versions of the serialisation)
• The serialiser put there a point which lives on the curve but is not specifically in the large subgroup (a random point on the curve has a 25% chance of being in that subgroup). This would mean serialisation needs to be fixed.
• A more obscure, one-off error in serialisation, for some random reason.