Accruent MC Error Message
500 error that starts showing up for all users
One of your Servers out of hard drive space?
It could be that your SQL or IIS Server ran out of hard drive space and that is causing errors to spiral that caused the APP pool to stop working. This will cause a lot more problems for eventually everyone if it is this is the cause.
Check under the Accruent MC section of our documentation for other more specific causes of 500 errors.