Yesterday we identified an issue with the SPS validator software related to the undelegate_tokens_multi function.
When a user attempted to undelegate multiple SPS delegations at once, the validator correctly checked each individual undelegation, but did not validate the total combined amount. As a result, when processing advanced to the execution stage, it could attempt to undelegate more SPS than the user actually had available, causing the transaction to fail and halt processing. The halt correctly prevented potential economic exploits, but does require us to release a patch to the software so that validators can continue processing blocks normally.
There is no new snapshot as the chain did not fork, but if you're running a validator, this upgrade is required to move past the block on which the network was stuck and to continue processing blocks normally:
https://github.com/TheSPSDAO/SPS-Validator/releases/tag/v1.3.1