All, I'll be releasing Cabal-1.6.0.2 soon. I've been testing with packages on hackage for regressions. However even with the regressions fixed there will be a small handful of packages that will break with the new release. This is because they are already incorrect it's just that this was previously hidden. All these errors get picked up now because the new Cabal version checks that header files and C libs can be found at configure time. This check is generally a great help to users. Unfortunately in the case of these packages it picks up issues that did not always previously cause build failure (though could cause failure in some configurations). So I'm sorry that these 6 package now break. They are all genuine pre-existing errors though and fixing them seems a small price to pay for a better user experience for the other 1000 packages on hackage. I'm cc'ing the maintainers of the 6 packages. There is no need to release immediately, in fact you may like to wait for the release and test against it yourself to confirm whatever fixes you make. These are the packages and their errors: digest-0.0.0.2: This lists zutil.u as an include file. This is just a spelling error. It should be zutil.h of course. This does break with ghc-6.8 using -fvia-C. The behaviour of ghc-6.10 masks this error. hopenssl-1.0: This lists <openssl/evp.h> as an include file. There is of course no such file. It should be openssl/evp.h instead. This does break with ghc-6.8 using -fvia-C. The behaviour of ghc-6.10 masks this error. libxml-0.1.1: This lists libxml/xmlIO.h as an include file. On my system at least this is found under /usr/include/libxml2 not /usr/include. The best solution here is probably to use pkg-config to find the right include dir. Cabal supports this directly via: pkgconfig-depends: libxml-2.0 Again this happens to work with ghc-6.10 because it does not really use headers when compiling, but it breaks with older ghc or non-ghc. plugins-1.4.0: This specifies Linker.h as an include file. This is from the ghc rts include files. However this file cannot be included on its own. It does not compile. It needs some other rts headers to be included first. This would have failed with ghc-6.8, only the package does not work with 6.8. It does not fail wit 6.10 because 6.10 doesn't really #include headers at all. riot-1.20080618: This specifies an include file that does not exist at configure time. It specifies a file under dist/ that would be generated by running hsc2hs. This is already incorrect, but happens to work with the default dist location and current layout. If this package were uploaded today it would be rejected. sqlite-0.4.2: This specifies a include file that is not a file, but is actually a directory. It looks like confusion. Thanks Duncan