Troubleshooting

There are two likely causes behind a failure to install from source.

Possible cause #1.  Outdated database used by groundhog to find packages.
This affects some 'recommended' packages  (typically 'MASS' or  'Matrix'), when attempting to load them with a groundhog day in 2022. To solve this issue, update groundhog's internal database by running:
groundhog:::load.cran.toc(TRUE)

(you do need three :::, not the usual two ::)

Possible cause #2.  Missing package in the operating system.
A more likely problem is actually unrelated to groundhog. It involves not having a piece of software that R needs to install packages from 'source'. If you read the error message in your console you are likely to find the piece of software that's missing indicated.

• • For Windows usually all you need is having R Tools installed. Visit our R Tools tab, or the official  R Tools page.
  • For Mac, the software you need can be found here: https://mac.r-project.org/tools/

• • For Unix there are a variety of separate packages that need to be installed, again, usually the error message you obtain when relying on groundhog.library(),   will indicate which package it is that you need.

MAC example
If on Mac Big Sur OSX 11, you run
groundhog.library('lme4', '2020-12-01')

the installation of the package Matrix will fail. Among the copious output in your console you will find this line indicating that gfortran is missing.

    ld: library not found for -lgfortran

You just need to install it from here https://mac.r-project.org/tools/, then Matrix, and thus lme4, will successfully install.

With groundhog v<2.0, conflicts with a different version of the same package would sometimes persist after restarting R session (when R Studio would automatically load needed packages) and the solution was to uninstall the packages creating the conflict. Since v2.0 that is handled automatically.

With groundhog v<1.5, older Windows machines would produce error 'This does not look like a tar archive'  when installing binaries.