Regular expression help and error (Regex: unmatched parentheses )

[Michael_Schyma1]

The regular expression is correct according to RegExr, but i keep on getting this error

Regex: unmatched parentheses

I am not understanding why my regular expression is not working. Here is what i have in Splunk Search:

rex field=_raw "Member:\W+Security.ID:\W+TARD\\(?<member_added>\S+)"

I just dont see it for whatever reason. Thanks guys

[Rob · Accepted solution]

I take it you are trying to escape a backslash character. In that case you need to use 3 backslashes in the rex command like this:

rex field=_raw "Member:\W+Security.ID:\W+TARD\\\(?<member_added>\S+)"

[raoul]

This works, but why? Why does Splunk require three? By my logic I am escaping a backslash - one other backslash should do the trick...