I ran across this today, when upgrading from CakePHP 1.2 to 1.3 on a CentOS box. Since the bug didn’t appear on Windows, after a bit of debugging I realized it was actually caused by a misconfiguration in the PCRE library that ships with RedHat and thus CentOS 5.x. It’s been reported to CakePHP but it’s not their fault, it just surfaces in View::element() because that uses Inflector::slug(), which in turn relies on PCRE. I guess this codepath has changed since 1.2, hence it showed up during the migration.
Update 2/8/11: If you’re on 64-bit, change the RPM upgrade line to be
rpm -Uvh /usr/src/redhat/RPMS/x86_64/pcre-6.6-2.7.x86_64.rpm /usr/src/redhat/RPMS/x86_64/pcre-devel-6.6-2.7.x86_64.rpm
Update 1/30/2012: See updated instructions for CakePHP 2.0.