Update Value of TwoDigitYearMax to 2049

src/libraries/System.Globalization.Calendars/tests/ThaiBuddhistCalendar/ThaiBuddhistCalendarToFourDigitYear.cs

@@ -16,12 +16,12 @@ public class ThaiBuddhistCalendarToFourDigitYear
         public void ToFourDigitYear(int year)
         {
             ThaiBuddhistCalendar calendar = new ThaiBuddhistCalendar();
-            calendar.TwoDigitYearMax = 2029;
+            calendar.TwoDigitYearMax = 2049;
             if (year > 99)
             {
                 Assert.Equal(year, calendar.ToFourDigitYear(year));
             }
-            else if (year > 29)
+            else if (year > 49)
             {
                 Assert.Equal(year + 1900, calendar.ToFourDigitYear(year));
             }

src/libraries/System.Private.CoreLib/src/System/Globalization/Calendar.cs

@@ -650,10 +650,10 @@ internal virtual bool IsValidDay(int year, int month, int day, int era)
         /// Returns and assigns the maximum value to represent a two digit year.
         /// This value is the upper boundary of a 100 year range that allows a
         /// two digit year to be properly translated to a four digit year.
-        /// For example, if 2029 is the upper boundary, then a two digit value of
-        /// 30 should be interpreted as 1930 while a two digit value of 29 should
-        /// be interpreted as 2029.  In this example, the 100 year range would be
-        /// from 1930-2029.  See ToFourDigitYear().
+        /// For example, if 2049 is the upper boundary, then a two digit value of
+        /// 30 should be interpreted as 1950 while a two digit value of 49 should
+        /// be interpreted as 2049.  In this example, the 100 year range would be
+        /// from 1950-2049.  See ToFourDigitYear().
         /// </summary>
         public virtual int TwoDigitYearMax
         {
@@ -667,9 +667,9 @@ public virtual int TwoDigitYearMax
 
         /// <summary>
         /// Converts the year value to the appropriate century by using the
-        /// TwoDigitYearMax property.  For example, if the TwoDigitYearMax value is 2029,
-        /// then a two digit value of 30 will get converted to 1930 while a two digit
-        /// value of 29 will get converted to 2029.
+        /// TwoDigitYearMax property.  For example, if the TwoDigitYearMax value is 2049,
+        /// then a two digit value of 50 will get converted to 1950 while a two digit
+        /// value of 49 will get converted to 2049.
         /// </summary>
         public virtual int ToFourDigitYear(int year)
         {

src/libraries/System.Private.CoreLib/src/System/Globalization/CalendarData.cs

@@ -40,7 +40,7 @@ internal sealed partial class CalendarData
         internal string[] saLeapYearMonthNames = null!; // Multiple strings for the month names in a leap year.
 
         // Integers at end to make marshaller happier
-        internal int iTwoDigitYearMax = 2029; // Max 2 digit year (for Y2K bug data entry)
+        internal int iTwoDigitYearMax = 2049; // Max 2 digit year (for Y2K bug data entry)
         private int iCurrentEra;  // current era # (usually 1)
 
         // Use overrides?
@@ -66,7 +66,7 @@ private static CalendarData CreateInvariant()
             invariant.sNativeName = "Gregorian Calendar";  // Calendar Name
 
             // Year
-            invariant.iTwoDigitYearMax = 2029; // Max 2 digit year (for Y2K bug data entry)
+            invariant.iTwoDigitYearMax = 2049; // Max 2 digit year (for Y2K bug data entry)
             invariant.iCurrentEra = 1; // Current era #
 
             // Formats

src/libraries/System.Private.CoreLib/src/System/Globalization/EastAsianLunisolarCalendar.cs

@@ -646,7 +646,7 @@ public override bool IsLeapYear(int year, int era)
             return InternalIsLeapYear(year);
         }
 
-        private const int DefaultGregorianTwoDigitYearMax = 2029;
+        private const int DefaultGregorianTwoDigitYearMax = 2049;
 
         public override int TwoDigitYearMax
         {

src/libraries/System.Private.CoreLib/src/System/Globalization/GregorianCalendar.cs

@@ -406,7 +406,7 @@ internal override bool TryToDateTime(int year, int month, int day, int hour, int
             return DateTime.TryCreate(year, month, day, hour, minute, second, millisecond, out result);
         }
 
-        private const int DefaultTwoDigitYearMax = 2029;
+        private const int DefaultTwoDigitYearMax = 2049;
 
         public override int TwoDigitYearMax
         {

src/libraries/System.Private.CoreLib/src/System/Globalization/JulianCalendar.cs

@@ -54,7 +54,7 @@ public class JulianCalendar : Calendar
         public JulianCalendar()
         {
             // There is no system setting of TwoDigitYear max, so set the value here.
-            _twoDigitYearMax = 2029;
+            _twoDigitYearMax = 2049;
         }
 
         internal override CalendarId ID => CalendarId.JULIAN;