If you get this error message in Resource Variance Inquiry form, Check Profile option “BOM: Hour UOM”.
If the value is null or having some other invalid values, change it to the UOM which is widely used in your instance to measure the resource usage (Ex: HRS, Minutes, Day, Year, etc…)
In my scenario it is HRS, hence I have entered that. It is always best to implement the action plan first in your test instance.
Now try opening the “Resource Variance Inquiry” form, it will list out the resource variances.