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Change DateTime Format {"MM/dd/yyyy"} to {"dd/MM/yyyy"} and time should remain same in Unity

I want to change DateTime now to the Format {"MM/dd/yyyy"} using this code.
string.Format("{0:MM:dd:yyyy}", DateTime.Now)
and saving it.
after getting saved string I get DateTime in format {"MM/dd/yyyy"} . Now I want to convert it in another format so I can Parse to DateTime. when I try to parse MM/dd/yyyy to DateTime got an error
"FormatException: String was not recognized as a valid DateTime."
Thanks in Advance.

You can rather use DateTime.ParseExact which allows you to specify the exact date format you are expeting the input to have.
For example
var now = DateTime.Now;
Debug.Log(now.ToString("dd.MM.yyyy"));
var example1 = now.ToString("MM/dd/yyyy");
Debug.Log(example1);
var readTime1 = DateTime.ParseExact(example1, "MM/dd/yyyy", CultureInfo.InvariantCulture);
Debug.Log(readTime1.ToString("dd.MM.yyyy"));
var example2 = now.ToString("dd/MM/yyyy");
Debug.Log(example2);
var readTime2 = DateTime.ParseExact(example2, "dd/MM/yyyy", CultureInfo.InvariantCulture);
Debug.Log(readTime2.ToString("dd.MM.yyyy"));
See Fiddle

The format is only relevant for display
If you save it in a C# DateTime variable, there is no "format" when saving it, this DateTime is a struct data type which is universal and not bound to any specific format
If you want to use a specific format for parsing, you can use:
// Parse date and time with custom specifier.
CultureInfo provider = CultureInfo.InvariantCulture;
dateString = "Sun 15 Jun 2008 8:30 AM -06:00";
format = "ddd dd MMM yyyy h:mm tt zzz";
DateTime myDate = DateTime.ParseExact(dateString, format, provider);
You can use CultureInfo to optimize your format for you needs
If there is a need to save it as "MM/dd/yyyy", your should save it as string
best regards

c# convert yyyymmdd text to dd/MM/yyyy

I have some text in rows as yyyymmdd (eg: 20181211) which I need to convert to dd/MM/yyyy
I am using:
cashRow["BusinessDate"] = Convert.ToDateTime(row.Cells[ClosingDate.Index].Value.ToString()).ToString("dd/MM/yyyy");
I get the error "string was not recognized as a valid DateTime.
Any ideas where I am going wrong?

You'll need to use ParseExact (or TryParseExact) to parse the date:
var date = "20181217";
var parsedDate = DateTime.ParseExact(date, "yyyyMMdd", System.Globalization.CultureInfo.InvariantCulture);
var formattedDate = parsedDate.ToString("dd/MM/yyyy", System.Globalization.CultureInfo.InvariantCulture)
Here we tell ParseExact to expect our date in yyyyMMdd format, and then we tell it to format the parsed date in dd/MM/yyyy format.
Applying it to your code:
cashRow["BusinessDate"] = DateTime.ParseExact(row.Cells[ClosingDate.Index].Value.ToString(), "yyyyMMdd", System.Globalization.CultureInfo.InvariantCulture).ToString("dd/MM/yyyy", System.Globalization.CultureInfo.InvariantCulture);

You have to use ParseExact to convert your yyyyMMdd string to DateTime as follows and then everything is okay.
cashRow["BusinessDate"] = DateTime.ParseExact(row.Cells[ClosingDate.Index].Value.ToString(), "yyyyMMdd", CultureInfo.InvariantCulture).ToString("dd/MM/yyyy");

As you already know the exact format of your input yyyyMMdd (eg: 20181211), just supply it to DateTime.ParseExact() and then call ToString() on the returned DateTime object.
string YourOutput = DateTime.ParseExact(p_dates, "yyyyMMdd", System.Globalization.CultureInfo.InvariantCulture).ToString("dd/MM/yyyy", System.Globalization.CultureInfo.InvariantCulture);

Try this:
cashRow["BusinessDate"] = row.Cells[ClosingDate.Index].Value.ToString("dd/MM/yyyy");

System.FormatException: String was not recognized as a valid DateTime - when trying to convert MM/DD/YYYY

I have following C# method:
DateTime ConvertStringToDate(string dateInString)
{
try {
//string SSD = dateInString;
//DateTime date = Convert.ToDateTime(SSD);
//string strDate = String.Format("{0:yyyy-MM-dd HH:mm:ss.fff}", date);
//return Convert.ToDateTime(strDate);
return DateTime.ParseExact(dateInString, "MM/dd/yyyy", CultureInfo.InvariantCulture);
}
catch (Exception) { }
return DateTime.Today;
}
The code in comment is another way I tried before.
I am in India and developing an ASP.NET WebForms application for my client in US. On one of its forms my client will enter the date in TextBox like 6/20/2018 which is MM/dd/yyyy format.
But in both the ways I am getting this error: System.FormatException: 'String was not recognized as a valid DateTime.'
I tried many solutions on SO but none of them are working.

return DateTime.ParseExact(dateInString, "M/d/yyyy", CultureInfo.InvariantCulture);
Check it here
The difference between my answer and Fabulous' one is that I also shortened dd to d so if your user writes 6/6/2018 it will work too

Your date format is MM/dd/yyyy and your input doesn't match. It is M/dd/yyyy
Based on your comment, to solve the 6/1/2018 issue, you'll need to do it as follows M/d/yyyy

Your format string is missing the AM/PM deisgnator:
return DateTime.ParseExact
(dateInString + " 12:00:00 AM", "MM/dd/yyyy hh:mm:ss tt", CultureInfo.InvariantCulture);
// Here ---------------------------------------------^

Try without concatenation with string " AM"

I was getting the same exception a couple of days ago when it was 9th of July, I simply appended a 0 with 9 to match the date format.
Try appending a 0 in your month to match the MM in your date format

Sometimes your system time and date format is not same as test format you can try to change system date and time format

If you want to convert this (01-01-2022) type of string into date
then try below code.
DateTime date = DateTime.ParseExact("01-01-2022", "MM-dd-yyyy", CultureInfo.InvariantCulture);
If you want to convert this (01/01/2022) type of string into date
then try below code.
DateTime date = DateTime.ParseExact("01-01-2022", "MM/dd/yyyy", CultureInfo.InvariantCulture);

Date format "dd/MM/yyyy" to "yyyy/MM/dd"

I know this question has been asked before and resolved using various methods.
I am converting a value from a string to a DateTime.
Throughout the project I have used the same CultureInfo, all strings that where converted to date where done using Convert.ToDateTime(), but now there is one text field that refuses to convert.
I have tried:
string date = "27/02/2013";
string startdated = (Convert.ToDateTime(date)).ToString("yyyy/MM/dd");
(converts to datetime and changes it back to sting in my required format. This works fine on everything else)
even
Datetime dt = Convert.toDateTime(date); doesn't work
DateTime.ParseExact(date, "yyyy/MM/dd", format); doesn't work
And all give me the same error "String was not recognized as a valid DateTime.". i receive my date value from a textbox with an ajax calender extender (CalendarExtender.Format = "dd/MM/yyyy" done for display purposes,this also works everywhere else i.e "dd/MM/yyyy" for display and "yyyy/MM/dd" for procedure) except this final value which simply will not change. Everthing is done via my machine with no external servers

Your input string is not in the same format as the format you provde DateTime.ParseExact with.
For this to work
DateTime.ParseExact(date, "yyyy/MM/dd", format);
You have to enter the date in year/month/day format. But your string is in day/month/year.
This should work better.
string date = "27/02/2013";
DateTime parsedDate = DateTime.ParseExact(date, "dd/MM/yyyy", CultureInfo.InvariantCulture);

Your date is date = "27/02/2013"; and your current format (in DateTime.ParseExact) is "yyyy/MM/dd", It should be:
"dd/MM/yyyy"
So the following code should work.
string date = "27/02/2013";
DateTime dt = DateTime.ParseExact(date, "dd/MM/yyyy", CultureInfo.InvariantCulture);
You can also use the format "d/M/yyyy" which would take care of single or double digit date/month.

Issue in Converting Date Time c#

I am facing an issue when converting the datetime
var date = DateTime.Now;
txtdate.Text = date.ToString("dd/MM/yyyy", CultureInfo.InvariantCulture);
//I need to pass it later to as a DateTime variable. When i re-convert it gives me an error)
DateTime dtReconvert =Convert.toDateTime(txtdate.Text); //Error String was not recognized as a valid DateTim
When i set the datetime to something like "01/01/2013"
and convert it to Date Time it not giving me any error.

Use DateTime.ParseExact with the format "dd/MM/yyyy"
DateTime dtObject = DateTime.ParseExact(txtdate.Text,
"dd/MM/yyyy",
CultureInfo.InvariantCulture);

try this
DateTime.ParseExact(txtdate.Text, "MM/dd/yyyy", System.Globalization.CultureInfo.InvariantCulture)
or
Convert.ToDateTime(txtdate.Text, CultureInfo.InvariantCulture)
Microsoft have adopted MM/dd/yyyy as a culture-agnostic format, it's an ambiguous format which isn't something that I would want to build a large system on.