DateTime errors in C#

This error makes zero sense to me because everything is a DateTime, there is literally nothing in the entire C# script that has to do with TimeSpan.

If anyone knows how to fix this i would appreciate it, also i am currently on Unity version 5.50f so in other words i’m not on the latest version reason being last time I tried installing the latest version my unity didn’t work for 2 weeks, if you think I need to update please let me know.

Subtraction with DateTime results in a TimeSpan and not a DateTime so DifDate should be TimeSpan and not a DateTime. Here is the doc.
Nothing to do with the Unity version it still uses the same .Net version.

Subtracting 2 Dates results in a Timespan. To get the date between 2 days use this code:

DateTime todaysDate = Convert.ToDateTime("12/25/2017");
DateTime otherDate = Convert.ToDateTime("11/25/2017");
TimeSpan timeDifference = todaysDate.Subtract(otherDate);
Debug.Log(timeDifference.TotalDays);

That should provide you with an answer.