Database Limit Error in Owner Limits

When saving the Server Owner Limits page (accessed via the Edit Owner Limits link), I get the following error:

Failed to save owner limits : Missing or invalid databases limit

Note that the "Maximum allowed databases" was already set to zero for this domain; I did not change it. However, Virtualmin apparently does not consider zero to be a valid entry here (which it should be).

Status: 
Closed (fixed)