When adding item to SPO List, ctx.ExecuteQuery Error occurs (sometimes)

i get this error stating:"ExecuteQuery" with "0" argument(s): "Input string was not in a correct format." while adding items to SPO List. but the problem is not with the code, it literally happens sometimes and doesn't happen other times.

I have checked all the data types, all null-handling and everything. but it doesn't work

sometimes it works and sometimes it doesn't (for the same data set)