Despite specifying --compiler with ghc 8.6.3, it still appears to be looking for 8.6.5. I'm open to fixes along another avenue as well:
$ stack --compiler=ghc-8.6.3 upgrade --jobs 1
Current Stack version: 1.7.1, available download version: 2.3.1
Newer version detected, downloading
Querying for archive location for platform: linux-arm-static
Querying for archive location for platform: linux-arm
Warning: Exception occured when trying to perform binary upgrade:
Control.Exception.Safe.throwString called with:
Unable to find binary Stack archive for platforms: linux-arm-static linux-arm
Called from:
throwString (src/Stack/Setup.hs:1860:21 in stack-1.7.1-BI2bgYdnvyK9S4nLtTY1aU:Stack.Setup)
Falling back to source upgrade
Selected mirror https://s3.amazonaws.com/hackage.fpcomplete.com/
Downloading timestamp
Downloading snapshot
Updating index
Updated package index downloaded
Update complete
Populated index cache.
Warning: /tmp/stack-upgrade-bb01a799/stack-2.3.1/stack.yaml: Unrecognized field in ProjectAndConfigMonoid: drop-packages
No setup information found for ghc-8.6.5 on your platform.
This probably means a GHC bindist has not yet been added for OS key 'linux-armv7', 'linux-armv7-ncurses6', 'linux-armv7-tinfo6'.
Supported versions: ghc-7.10.2, ghc-7.10.3, ghc-8.0.1, ghc-8.0.2, ghc-8.2.1, ghc-8.2.2, ghc-8.6.3, ghc-8.10.1