I did a complete reset and restart of Haskell & Cabal, and trying to re-install my former packages on a new clean system, most went easily but there are already a number which would not install. (Deleted .ghc, .cabal, and .sandbox; reinstalled Platform). 1) "ghc-pkg check" indicates a lot of issues (although most seemed to be warnings about missing .hi or haddock html files). Many seem to be related to looking for older versions, e.g. it complains that: There are problems in package Win32-2.2.2.0: Warning: library-dirs: E:\Plang\Haskell Platform\lib\Win32-2.2.2.0 doesn't exist or isn't a directory Warning: include-dirs: E:\Plang\Haskell Platform\lib\Win32-2.2.2.0\include doesn't exist or isn't a directory import-dirs: E:\Plang\Haskell Platform\lib\Win32-2.2.2.0 doesn't exist or isn't a directory cannot find any of ["libHSWin32-2.2.2.0.a","libHSWin32-2.2.2.0.p_a","libHSWin32-2.2.2.0-ghc7.8.3.so","libHSWin32-2.2.2.0- ghc7.8.3.dylib","HSWin32-2.2.2.0-ghc7.8.3.dll"] on library path And indeed it is not there, but Win32-2.3.0.2 is present, and similarly for most all others that I see. So why are these being reported as problems, and what to do? 2) cabal install of several of my previous packages fails; is there just some intrinsic incompatibility of these packages, or some other error? An example: C:\Users\myUser\.cabal-sandbox>cabal install cgi Resolving dependencies... In order, the following would be installed: exceptions-0.6.1 (reinstall) changes: mtl-2.1.3.1 -> 2.2.1, transformers-0.3.0.0 -> 0.4.2.0 network-2.6.0.2 (new version) cgi-3001.2.2.0 (new version) cabal: The following packages are likely to be broken by the reinstalls: temporary-1.2.0.3 ghc-mod-5.2.1.2 either-4.3.3 monad-journal-0.7 Use --force-reinstalls if you want to install anyway. 3) ghc-pkg check indicates a lot of broken packages for a new installation, Although all those that I checked of these are from old versioning as above, and there really is a good and more current version installed: The following packages are broken, either because they have a problem listed above, or because they depend on a broken package. Win32-2.2.2.0 time-1.4 template-haskell-2.7.0.0 regex-base-0.93.2 process-1.1.0.1 pretty-1.1.1.0 parsec-3.1.3 old-time-1.1.0.0 old-locale-1.0.0.4 integer-gmp-0.4.0.0 HTTP-4000.2.5 hpc-0.5.1.1 hoopl-3.8.7.3 haskell98-2.0.0.1 haskell2010-1.1.0.1 haskell-platform-2012.4.0.0 ghc-prim-0.2.0.0 ghc-7.4.2 filepath-1.3.0.0 fgl-5.4.2.4 extensible-exceptions-0.1.1.4 directory-1.1.0.2 deepseq-1.3.0.0 containers-0.4.2.1 cgi-3001.1.7.4 Cabal-1.14.0 bytestring-0.9.2.1 binary-0.5.1.0 base-4.5.1.0 array-0.4.0.0 zlib-0.5.4.0 xhtml-3000.2.1 vector-0.10.0.1 transformers-0.3.0.0 text-0.11.2.3 syb-0.3.7 stm-2.4 split-0.2.1.1 regex-posix-0.95.2 regex-posix-0.95.2 regex-compat-0.95.1 regex-compat-0.95.1 random-1.0.1.1 QuickCheck-2.5.1.1 primitive-0.5.0.1 parallel-3.2.0.3 OpenGL-2.2.3.1 network-2.3.1.0 HUnit-1.2.5.1 -------------------------------------------