[c#] Subtract days from a DateTime

I have the following code in my C# program.

DateTime dateForButton =  DateTime.Now;  
dateForButton = dateForButton.AddDays(-1);  // ERROR: un-representable DateTime

Whenever I run it, I get the following error:

The added or subtracted value results in an un-representable DateTime.
Parameter name: value

Iv'e never seen this error message before, and don't understand why I'm seeing it. From the answers Iv'e read so far, I'm lead to believe that I can use -1 in an add operation to subtract days, but as my question shows this is not the case for what I'm attempting to do.

I've had issues using AddDays(-1).

My solution is TimeSpan.

DateTime.Now - TimeSpan.FromDays(1);

You can do:

DateTime.Today.AddDays(-1)

You can use the following code:

dateForButton = dateForButton.Subtract(TimeSpan.FromDays(1));

DateTime dateForButton = DateTime.Now.AddDays(-1);

Using AddDays(-1) worked for me until I tried to cross months. When I tried to subtract 2 days from 2017-01-01 the result was 2016-00-30. It could not handle the month change correctly (though the year seemed to be fine).

I used date = Convert.ToDateTime(date).Subtract(TimeSpan.FromDays(2)).ToString("yyyy-mm-dd"); and have no issues.

The object (i.e. destination variable) for the AddDays method can't be the same as the source.

Instead of:

DateTime today = DateTime.Today;
today.AddDays(-7);

Try this instead:

DateTime today = DateTime.Today;
DateTime sevenDaysEarlier = today.AddDays(-7);

The dateTime.AddDays(-1) does not subtract that one day from the dateTime reference. It will return a new instance, with that one day subtracted from the original reference.

DateTime dateTime = DateTime.Now;
DateTime otherDateTime = dateTime.AddDays(-1);

Instead of directly decreasing number of days from the date object directly, first get date value then subtract days. See below example:

DateTime SevenDaysFromEndDate = someDate.Value.AddDays(-1);

Here, someDate is a variable of type DateTime.