1. In the Hardware status tab of vSphere client select system event log and in the reset event log select update.
Now Reset the sensors (and even the host if you can do it) may fix your problem.
2. Otherwise you can reset watchdog service in a SSH access by running following command
and click update in alert tab again.Please mark my comment as the Correct Answer if this solution resolved your problem
These Memory errors are Hardware issues, sometime these can resolve by reseating the Bad DIMM(RAM) to the same slot. Sometimes changing the slot (In HPE servers there is a sequence of inserting DIMM to DIMM Slots according to Processors A and B)
For resolution you must need to log case with vendor either the DIMM is faulty so it will re-appear after changing the slot as well, so they have to replace this bad DIMM. Either theycan ask you to upgrade your BIOS or Firmware depending on your hardware.
Check how much RAM is there on your physcial server and how much is the ESXi host able to detect? If its low then DIMM is faulty. And RAM is showing correct then check with your hardware vendor . And if you are proficient in Hardware and know the RAM slot sequence you can either try re-seating the DIMM to other or same slot.
NOTE: Before doing this make sure there are no VMs on host and it must be in maintenance mode.