r1555551 introduced "named groups" feature, and this uses PCRE_DUPNAMES. PCRE of Red Hat Enterprise Linux / CentOS 5 is 6.6. Yes, this is too old. PCRE_DUPNAMES is not defined on PCRE 6.6, so causes build failure. Issues: 1) Regression I have not try, but accourding to the changes, 2.4.7 can build on RHEL 5, but 2.4.8 not. 2) Fails on make "configure" is succeeded, but "make" is failed with unkind message. 3) not documented I can't find any document that says Apache 2.4 needs PCRE 6.7 and later. If we should correct the regression, we should apply rpluem's patch http://mail-archives.apache.org/mod_mbox/httpd-dev/201401.mbox/%3C52CFAC91.5080707@apache.org%3E and document. http://mail-archives.apache.org/mod_mbox/httpd-dev/201401.mbox/%3CFD95E1EB-705D-4B57-91E5-A7D8C05DF421@sharp.fm%3E If we decide not to correct the regression, we should backport r1612921 (and r1612945 ? )