Thanks - I did try a cabal install xxx" for the missing packages, a few seemed to succeed, a few failed, and now I get a longer list of overall failures! :-) ... There are problems in package scion-0.1.0.9: dependency "AttoJson-0.5.10-4932e72997280d8c2e35b4aca3328284" doesn't exist dependency "binary-0.5.0.2-72c84eaab351d41e936261d8d5d416f5" doesn't exist dependency "list-tries-0.4.1-a2fcbc51b309eb5aade37b40c6ef166e" doesn't exist There are problems in package bytestring-show-0.3.4: dependency "binary-0.5.0.2-72c84eaab351d41e936261d8d5d416f5" doesn't exist There are problems in package carray-0.1.5: dependency "binary-0.5.0.2-72c84eaab351d41e936261d8d5d416f5" doesn't exist dependency "ix-shapable-0.1.0-68747ed518a0145d47f8095a08e0bcbb" doesn't exist ... The following packages are broken, either because they have a problem listed above, or because they depend on a broken package. warp-0.4.6.3 tagsoup-0.12.3 simple-sendfile-0.2.0 blaze-builder-enumerator-0.2.0.3 scion-0.1.0.10 aeson-0.3.2.11 hashable-1.1.2.1 blaze-textual-0.2.0.4 double-conversion-0.2.0.1 derive-2.5.4 hoogle-4.2.6 warp-0.4.3 wai-0.4.1 simple-sendfile-0.1.2 http-types-0.6.5.1 case-insensitive-0.3.0.1 blaze-builder-enumerator-0.2.0.2 bmp-1.1.2.1 scion-0.1.0.9 bytestring-show-0.3.4 carray-0.1.5 unordered-containers-0.1.4.2 I tried an install (reinstall?) of the things it lists as missing, and generally they report "already installed". For example;

cabal install AttoJson

Resolving dependencies... No packages to be installed. All the requested packages are already installed. If you want to reinstall anyway then use the --reinstall flag. (same for binary, list-tries, ix-shapable, ...)

ghc --version

The Glorious Glasgow Haskell Compilation System, version 7.0.3 Some things do seem to resolve after a few iterations through re-installations, but others seem stuck, and overall the process seems like a mess.

What is the remedy (is there a simple remedy?) if "ghc-pkg check" reports something amiss?

In this case, the simple remedy is to reinstall the packages which the error messages say do

not exist (blaze-builder, hashable, AttoJson) and then reinstall any packages you want to use

which depend on them.

-Brent