Argument is missing in '\' escape sequence.
This error generally occurs during search or replace when regular expressions or wildcards are used in a search string. This error can be caused by a single backslash (\) at the end of a pattern or by \x or \u entered without a valid hexadecimal Unicode character.
To correct this error
To search using the regular expression escape character, enter \.
To search for a Unicode character, enter \x or \u followed by a valid Unicode value.
To search for the literal backslash, use \\.
See Also
Reference
Regular Expressions (Visual Studio)