When I control my sheet name by flow variable, the file name still can't be empty. I have to insert atleast one character to be able to save the settings. Perhaps you could fix this and grey out the file name box when it is controlled by a variable.
yes we are aware of this and will work on a solution. It is a tradeoff between a moreflexible configuration for flow variables and a less comfortable solution for the non flow variable case.
I think the best solution would be that once the flow variable is turned on, it overrides the other settings, and with that also the error message. My programming knowledge doesnt go much futher then VBA and some basic Java lines, but I think this situation would be perfect for an IF switch of some sort.