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[...] Can you get more info about what the linker error is?

Indeed, the linker exiting with status 1 without any stderr message sounds like your linker is crashing. take the last `ghc` invocation it makes, run that directly and add `-v` to that to get GHC's verbose output, which will show you the full linker invocation

I don't know yet what causes the linker to crash, but I found a work-around: If I download any pandoc version, extract it and run `stack build` inside that directory, it is fine. So I created a symlink to that local pandoc dir inside my package root and made pandoc a part of my own package. Then everything builds all right. Hence there must be something going wrong when stack downloads and builds pandoc somewhere inside .stack-work/. It seems difficult to just run the last sub-command as Niklas suggests, because after the crash all the temporary files of the failed build are gone. But I'll keep investigating, thanks for the suggestions! Olaf