“After block 855000, clients enforce the mandatory upgrade.”
Find the new version here
Further info here:
“As of approx. 3 days ago, some nodes started logging the error ‘BAD CPID’ - and we started to have a consensus issue. …”
We are contacting exchanges, … to stop ASAP their wallets, see progress here.
Hi,
please ensure that you are now running the latest version 3.5.8.7,
since there was a mandatory hardfork (A).
The hardfork was successful and we are in the process of confirming all exchanges and services are on the latest version
to ensure a smooth experience going forward.
We will contact you again in 24-48hrs when the process is complete.
Erkan
(A) https://github.com/gridcoin/Gridcoin-Research/releases/tag/3.5.8.7
Hello,
we’ve released yesterday the MANDATORY version 3.5.8.8 (A) (B) which fixes the problem that some wallets could not get any new blocks.
Please do upgrade and check that you’re on the correct chain: ©.
The mandatory upgrade block was at: #860500 (currently we’re at block #860811)
We are in the process of confirming all exchanges and services are on the latest version to ensure a smooth experience going forward.
Erkan YILMAZ
(A) https://github.com/gridcoin/Gridcoin-Research/releases/tag/3.5.8.8b
(B) https://steemit.com/gridcoin/@erkan/mandatory-gridcoin-version-3-5-8-8-block-860500
© in your wallet’s debug console type, e.g.: getblockhash 860790 => that should give you hash = a03c32b2f9dc0cc371b060cf556aff605484141fb8b12c67e8e766a0292d9146
Hello again,
several users have been experiencing further sync/forking issues in Gridcoin version 3.5.8.8 since yesterday 
Please shut down the Gridcoin wallet and hereby extend the maintenance period for a few days until things have become stable again.
We will inform you again!
Sorry for the inconvenience,
Erkan YILMAZ