Today counterparty releases version 9.55.4 which includes a hotfix for an uncaught exception which could cause a Counterparty server to stop operating normally.
There is no mandatory upgrade block for this release. However, all users are encouraged to upgrade as soon as possible.
Upgrade Procedure
For those running a federated node with no front-end:
fednode update counterparty counterparty-testnet
For those running a full federated node with counterwallet:
fednode update
For standalone / manual installations:
pip install --upgrade counterparty-lib==9.55.4