Question:
I saw the below error when running bills

Answer:
The Billing Wizard has a number of problems.
One of them is this screen with gobbly gook that doesn't mean anything to anyone. The performance of this screen is also bad with large systems.
Another is all those checks that takes so much CPU and then they get ignored by most people anyway.

You can already use the new methodology under 'Tools->RunBill'. It does not throw you with a Wizard interface, or all those checks, or the funny screen: if the bill run takes long, it puts it on the Report Queue, and you can carry on with other things while it is busy.
The way 'Run Bill' does the checks is pre-emptively. As we call in the meters every day, we continually check the data. If anything happens that makes the data questionable, we log an event, that 'invalidates' the meter. You can choose on the Meter Event setup for each meter which events make a meter trip validation. 'Run Bill' does not allow you to run a bill on possibly questionable data. We still allow Provisional Bills, though.
To validate the data, go to the Validation Screen, and click on the button next to it if you can clear the data. If you have reservations, but want billing to go ahead, you can log your reservations against the events also. That also ties in to the Fault Log system.
It should be more efficient for you to run your bills and check your data this way: looking at the problem meter list every day and looking at the validation screen every day, since you will have less false negatives to check, and the customer's data will be fixed sooner if it goes wrong.
In other words, please ignore that 'error' you saw. It was probably a meter without data. If you do Run Bill, it will tell you which accounts it can run bills for, and which not (you can also use Sets to specify which meter accounts to try); and if a meter has not called in, it will refuse to run that bill, so using Run Bill you would not have encountered this problem in the first place.
Please try it and let me know what you think.