nenumerická hodnota narazila na php
Not exactly the issue you had but the same error for people searching.
This happened to me when I spent too much time on JavaScript.
Coming back to PHP I concatenated two strings with "+" instead of "." and got that error.
nevyčíslitelná hodnota narazila na php
when this error is occuring make sure not to concatenate
anything like $fname+" "+$lname, we get error when we do
that, so when i did like $fname,$lname i got it perfect.