I tried to render the expression "invalid at computed-value time" into very understandable Russian as "недопустимое значение", and so trimmed in a way that retains no real essentials. I really don't want to say "invalid value".

Let me explain... this is a computing term. For example, I have a function, an input value and a conditional statement that defines if an output value returned by the function is acceptable. I don't know if the input value is valid to be taken as an input because it depends on what the output value is. Later, at computation time, the output — the computed value — proves to be unacceptable, so the input value is invalid at computed-value time.

What would be the accurate rendering of the expression, so that it never needs to be explained in order to be properly understood?