If you are the owner of an MX500 SSD from Crucial, be aware and don't update your firmware just yet if you grabbed the latest build and did not flash just yet. 

An issue was discovered with the latest build version M3CR033. Roughly late September users reported that a firmware patch M3CR033 for MX500 SSDs could be propagated. Downloading the update itself and trying to install it also turned out to fail. The firmware should have solved an issue with SATA protocol errors and certain RAID configurations.

Meanwhile, the new firmware from Crucial's support page has disappeared. In fact, all versions have been removed, the site reports that no firmware updates are currently available. Owners of an MX500 can therefore not update their SSD for the moment. An affected reader from Computerbase received a short statement from Crucial support via email, confirming a problem with the firmware update that should be fixed soon. It is unclear whether older firmware updates such as from version 022 to version 023 will soon be possible again.

Crucial pulls MX500 SSD firmwares from website due to issues