[Haskell-cafe] "Could not list sources" warning in sandboxed project with add-source deps

I'm getting a warning

...

Warning: Could not list sources of the add-source dependency 'xyz'. Skipping the timestamp check.

when building a sandboxed project with add-source dependencies.  I tried increasing the verbosity of cabal, but it still won't tell me what's going wrong so I can fix it.

Any suggestions on how to debug or fix this? Check the output of `cabal sandbox list-sources`. A likely cause is

Thanks for the quick reply, Mikhail, but no: the output of "cabal sandbox list-sources" looks fine. Any other ideas, anyone? --Eric On Friday, August 14, 2015 2:41 PM, Mikhail Glushenkov wrote: Hi, On 14 August 2015 at 21:00, Eric wrote: that one of add-source dependencies refers to a non-existent directory.