Powershell - ParseExact with 3 argument(s): String was not recognized as a valid DateTime

Powershell Code - ParseExact Date Conversion - String not recognized as valid DateTime

Windows Powershell

Goal:  Read and validate a string-date (with a known and expected format). 

Guarding against February 31st and stuff like that

Technique:

Cast the string into a [datetime].
Use ParseExact to convert the date

Use try-catch to detect detect failures.

Code:

[DateTime]$dtconvertedDate           #Declare DateTime Variable
[string]$strmyDate = "01/01/2025"    #Variable to test

try
{
   # Cast the ParseExact as [dateTime]

   # Unsafe

   $dtconvertedDate = [datetime]::ParseExact($strmyDate, "MM/dd/yyyy", $null)

   # Safer
   $dtconvertedDate = [datetime]::ParseExact($strmyDate.Trim(), "M/d/yyyy", $null)
}

catch

{
   # not illustrated -- not a date
}

Possible errors:

Exception calling "ParseExact" with "3" argument(s): "String was not recognized as a valid DateTime."

Possible answers:

-  $strmyDate  is from an Excel-exported CSV or tab file.   Be sure to .Trim().  Unsafe otherwise.

-  Mask  "MM/dd/yyyy" is case-sensitive!

-  Mask "MM/dd/yyyy"  can be, but is not always safe. 
    Date strings with leading zeros vs not:  "1/17/2025" -- MM/dd will fail.
    Use "M/d/yyyy"

-  Mask in wrong format:  MM-dd-yyyy  vs MM/dd/yyyy
    hyphens vs slash.  ParseExact with a mask cares.