DateTime Manipulation - String was not recognized as a valid DateTime

in addition to @supermanPunch also find following firstAid sheet introducing to this topic and also showing analysis techniques

:ambulance: :sos: [FirstAid] Datatable: Debug & Analysis invalid DateTime Strings / String to DateTime Parsing Issues - News / Tutorials - UiPath Community Forum

Same as discussed by Arpan the multiple formats were handled with a format array

About the DateDiff function take a note that not fractions of the selected unit is returned. When this is needed / important let us know for presenting additional techniques