An hour ago, Proposal 117 was executed, which updated the price feed that Compound v2 uses. This price feed contained an error that is causing transactions for ETH suppliers and borrowers to revert. Effectively, the cETH market is temporarily frozen.
OpenZeppelin, Chainlink, Compound Labs, and many members of the community are working to diagnose and fix this issue ASAP; GFX has created Proposal 119 which will revert the price feed to it’s original state.
You can still supply Ether collateral, and no users should be at risk of liquidation, or at risk of losing funds. If you have any questions, please join the community in Discord.