The following error is being reported numerous times around the site.

Warning: Invalid CRT parameters detected in D:\xampp\htdocs\moodle_master\lib\moodlelib.php on line 1975

This is caused by a change made in MDL-6102 in an attempt to remove leading zeros from time values. The format sequence %I was replaced with %l (lower-case L) in lang/en/langconfig.php, however this is not recognised by the libraries used to power Apache under Windows.

I'm not sure why this change was made. The userdate() function already strips leading zeros, so this change would have had no effect. Also the added stripping of double-spaces in userdate(), added with the fix in MDL-6102 is probably not needed.