homebrew-cask: brew cask install little-snitch - "Filename has an unknown suffix" error

General troubleshooting steps

I understand that if I ignore these instructions, my issue may be closed without review.
I have retried my command with --force.
I ran brew update-reset && brew update and retried my command.
I ran brew doctor, fixed as many issues as possible and retried my command.
I have checked the instructions for reporting bugs.
I made doubly sure this is not a checksum does not match error.

Description of issue

Okay, firstly apologies. This may be an inappropriate issue being raised, given that I’m now running Big Sur, but:

When running Catalina I brew cask install little-snitch-ed
When Big Sur came out I manually upgraded to Little Snitch 5
When the cask was updated I decided to throw caution to the wind and brew cask uninstall little-snitch, intending to then do the next step
Attempted brew cask install little-snitch

I’ve tried, the following, to no avail:

brew update-reset && brew update
brew cask uninstall --force little-snitch
brew cask zap --force little-snitch

~~I’ve also tried manually editing the formula to the 4.X version so that I can proceed through the workflow I did before I brew cask uninstall little-snitch to no avail.~~

There seems to be something left that it’s trying to purge, to no avail. I’m understanding this to be the case from ==> Purging files for version 5.0.2 of Cask little-snitch when little-snitch is not deemed to be installed.

If I could please ask for someone’s assistance on this, it would be tremendously appreciated! I totally appreciate that Big Sur is currently unsupported but this is doing my absolute nut and not sure it’s Big Sur related specifically (I could be wrong). Have been attempted to resolve this specific issue for over three hours, now. Many thanks!

Command that failed

brew cask install little-snitch

Output of command with `--verbose --debug`

Have shortened unique folder names to xxx and yyy

==> Cask::Installer#install
==> Printing caveats
==> Cask::Installer#fetch
==> Downloading
==> Downloading https://www.obdev.at/downloads/littlesnitch/LittleSnitch-5.0.2.dmg
/usr/bin/curl --disable --globoff --show-error --user-agent Homebrew/2.5.10-14-g8561fbf\ \(Macintosh\;\ Intel\ Mac\ OS\ X\ 11.0.1\)\ curl/7.64.1 --header Accept-Language:\ en --retry 3 --location --silent --head --request GET https://www.obdev.at/downloads/littlesnitch/LittleSnitch-5.0.2.dmg
Already downloaded: /Users/peter/Library/Caches/Homebrew/downloads/810ca3f4ebdb527ef9c8799a7f6dae431b0029c480a0e41aa57f3a248ae3ac64--LittleSnitch-5.0.2.dmg
==> Checking quarantine support
/usr/bin/xattr
/usr/bin/swift /usr/local/Homebrew/Library/Homebrew/cask/utils/quarantine.swift
==> Quarantine is available.
==> Verifying Gatekeeper status of /Users/peter/Library/Caches/Homebrew/downloads/810ca3f4ebdb527ef9c8799a7f6dae431b0029c480a0e41aa57f3a248ae3ac64--LittleSnitch-5.0.2.dmg
/usr/bin/xattr -p com.apple.quarantine /Users/peter/Library/Caches/Homebrew/downloads/810ca3f4ebdb527ef9c8799a7f6dae431b0029c480a0e41aa57f3a248ae3ac64--LittleSnitch-5.0.2.dmg
==> /Users/peter/Library/Caches/Homebrew/downloads/810ca3f4ebdb527ef9c8799a7f6dae431b0029c480a0e41aa57f3a248ae3ac64--LittleSnitch-5.0.2.dmg is quarantined
==> Downloaded to -> /Users/peter/Library/Caches/Homebrew/downloads/810ca3f4ebdb527ef9c8799a7f6dae431b0029c480a0e41aa57f3a248ae3ac64--LittleSnitch-5.0.2.dmg
tar tf /Users/peter/Library/Caches/Homebrew/downloads/810ca3f4ebdb527ef9c8799a7f6dae431b0029c480a0e41aa57f3a248ae3ac64--LittleSnitch-5.0.2.dmg
/usr/local/Homebrew/Library/Homebrew/brew.rb (Formulary::FormulaLoader): loading /usr/local/Homebrew/Library/Taps/homebrew/homebrew-core/Formula/xz.rb
All Formula dependencies satisfied.
==> Verifying SHA-256 checksum for Cask 'little-snitch'.
==> Installing Cask little-snitch
==> Cask::Installer#stage
==> Extracting primary container
==> Using container class UnpackStrategy::Xz for /Users/peter/Library/Caches/Homebrew/downloads/810ca3f4ebdb527ef9c8799a7f6dae431b0029c480a0e41aa57f3a248ae3ac64--LittleSnitch-5.0.2.dmg
/usr/bin/env PATH=/usr/local/opt/xz/bin:/usr/local/Homebrew/Library/Homebrew/shims/scm:/usr/bin:/bin:/usr/sbin:/sbin unxz -T0 -- /var/folders/f5/xxx/T/yyy/LittleSnitch-5.0.2.dmg
unxz: /var/folders/f5/xxx/T/yyy/LittleSnitch-5.0.2.dmg: Filename has an unknown suffix, skipping
==> Purging files for version 5.0.2 of Cask little-snitch
Error: Failure while executing; `/usr/bin/env PATH=/usr/local/opt/xz/bin:/usr/local/Homebrew/Library/Homebrew/shims/scm:/usr/bin:/bin:/usr/sbin:/sbin unxz -T0 -- /var/folders/f5/xxx/T/yyy/LittleSnitch-5.0.2.dmg` exited with 2. Here's the output:
unxz: /var/folders/f5/xxx/T/yyy/LittleSnitch-5.0.2.dmg: Filename has an unknown suffix, skipping

/usr/local/Homebrew/Library/Homebrew/system_command.rb:194:in `assert_success!'
/usr/local/Homebrew/Library/Homebrew/system_command.rb:62:in `run!'
/usr/local/Homebrew/Library/Homebrew/system_command.rb:37:in `run'
/usr/local/Homebrew/Library/Homebrew/system_command.rb:41:in `run!'
/usr/local/Homebrew/Library/Homebrew/system_command.rb:27:in `system_command!'
/usr/local/Homebrew/Library/Homebrew/unpack_strategy/xz.rb:32:in `extract_to_dir'
/usr/local/Homebrew/Library/Homebrew/unpack_strategy.rb:141:in `extract'
/usr/local/Homebrew/Library/Homebrew/unpack_strategy.rb:148:in `block in extract_nestedly'
/System/Library/Frameworks/Ruby.framework/Versions/2.6/usr/lib/ruby/2.6.0/tmpdir.rb:93:in `mktmpdir'
/usr/local/Homebrew/Library/Homebrew/unpack_strategy.rb:145:in `extract_nestedly'
/usr/local/Homebrew/Library/Homebrew/cask/installer.rb:200:in `extract_primary_container'
/usr/local/Homebrew/Library/Homebrew/cask/installer.rb:79:in `stage'
/usr/local/Homebrew/Library/Homebrew/cask/installer.rb:103:in `install'
/usr/local/Homebrew/Library/Homebrew/cask/cmd/install.rb:79:in `block in install_casks'
/usr/local/Homebrew/Library/Homebrew/cask/cmd/install.rb:78:in `each'
/usr/local/Homebrew/Library/Homebrew/cask/cmd/install.rb:78:in `install_casks'
/usr/local/Homebrew/Library/Homebrew/cask/cmd/install.rb:43:in `run'
/usr/local/Homebrew/Library/Homebrew/cask/cmd/abstract_command.rb:108:in `run'
/usr/local/Homebrew/Library/Homebrew/cask/cmd.rb:190:in `run'
/usr/local/Homebrew/Library/Homebrew/cask/cmd.rb:124:in `run'
/usr/local/Homebrew/Library/Homebrew/cmd/cask.rb:15:in `cask'
/usr/local/Homebrew/Library/Homebrew/brew.rb:119:in `<main>'

Output of `brew doctor --verbose`

==> Cask Environment Variables:
BUNDLE_PATH
CHRUBY_VERSION
GEM_HOME
GEM_PATH
HOMEBREW_CASK_OPTS
LC_ALL
PATH
RBENV_VERSION
RUBYLIB
RUBYOPT
RUBYPATH
SHELL
==> $LOAD_PATHS
/usr/local/Homebrew/Library/Homebrew/vendor/bundle/bundler/../ruby/2.6.0/gems/spoom-1.0.4/lib
/usr/local/Homebrew/Library/Homebrew/vendor/bundle/bundler/../ruby/2.6.0/gems/thor-1.0.1/lib
/usr/local/Homebrew/Library/Homebrew/vendor/bundle/bundler/../ruby/2.6.0/gems/sorbet-runtime-stub-0.2.0/lib
/usr/local/Homebrew/Library/Homebrew/vendor/bundle/bundler/../ruby/2.6.0/gems/ruby-macho-2.2.0/lib
/usr/local/Homebrew/Library/Homebrew/vendor/bundle/bundler/../ruby/2.6.0/gems/rubocop-sorbet-0.5.1/lib
/usr/local/Homebrew/Library/Homebrew/vendor/bundle/bundler/../ruby/2.6.0/gems/rubocop-rspec-2.0.0/lib
/usr/local/Homebrew/Library/Homebrew/vendor/bundle/bundler/../ruby/2.6.0/gems/rubocop-performance-1.8.1/lib
/usr/local/Homebrew/Library/Homebrew/vendor/bundle/bundler/../ruby/2.6.0/gems/unicode-display_width-1.7.0/lib
/usr/local/Homebrew/Library/Homebrew/vendor/bundle/bundler/../ruby/2.6.0/gems/ruby-progressbar-1.10.1/lib
/usr/local/Homebrew/Library/Homebrew/vendor/bundle/bundler/../ruby/2.6.0/gems/rubocop-ast-1.1.1/lib
/usr/local/Homebrew/Library/Homebrew/vendor/bundle/bundler/../ruby/2.6.0/gems/rspec-wait-0.0.9/lib
/usr/local/Homebrew/Library/Homebrew/vendor/bundle/bundler/../ruby/2.6.0/gems/rspec-retry-0.6.2/lib
/usr/local/Homebrew/Library/Homebrew/vendor/bundle/bundler/../ruby/2.6.0/gems/rspec-its-1.3.0/lib
/usr/local/Homebrew/Library/Homebrew/vendor/bundle/bundler/../ruby/2.6.0/gems/rspec-3.10.0/lib
/usr/local/Homebrew/Library/Homebrew/vendor/bundle/bundler/../ruby/2.6.0/gems/rspec-mocks-3.10.0/lib
/usr/local/Homebrew/Library/Homebrew/vendor/bundle/bundler/../ruby/2.6.0/gems/rspec-expectations-3.10.0/lib
/usr/local/Homebrew/Library/Homebrew/vendor/bundle/bundler/../ruby/2.6.0/gems/rspec-core-3.10.0/lib
/usr/local/Homebrew/Library/Homebrew/vendor/bundle/bundler/../ruby/2.6.0/gems/rspec-support-3.10.0/lib
/usr/local/Homebrew/Library/Homebrew/vendor/bundle/bundler/../ruby/2.6.0/gems/ronn-0.7.3/lib
/usr/local/Homebrew/Library/Homebrew/vendor/bundle/bundler/../ruby/2.6.0/gems/regexp_parser-1.8.2/lib
/usr/local/Homebrew/Library/Homebrew/vendor/bundle/bundler/../ruby/2.6.0/gems/rdiscount-2.2.0.2/lib
/usr/local/Homebrew/Library/Homebrew/vendor/bundle/bundler/../ruby/2.6.0/extensions/universal-darwin-19/2.6.0/rdiscount-2.2.0.2
/usr/local/Homebrew/Library/Homebrew/vendor/bundle/bundler/../ruby/2.6.0/gems/pry-0.13.1/lib
/usr/local/Homebrew/Library/Homebrew/vendor/bundle/bundler/../ruby/2.6.0/gems/plist-3.5.0/lib
/usr/local/Homebrew/Library/Homebrew/vendor/bundle/bundler/../ruby/2.6.0/gems/patchelf-1.3.0/lib
/usr/local/Homebrew/Library/Homebrew/vendor/bundle/bundler/../ruby/2.6.0/gems/parlour-4.0.1/lib
/usr/local/Homebrew/Library/Homebrew/vendor/bundle/bundler/../ruby/2.6.0/gems/rainbow-3.0.0/lib
/usr/local/Homebrew/Library/Homebrew/vendor/bundle/bundler/../ruby/2.6.0/gems/parser-2.7.2.0/lib
/usr/local/Homebrew/Library/Homebrew/vendor/bundle/bundler/../ruby/2.6.0/gems/parallel_tests-3.3.0/lib
/usr/local/Homebrew/Library/Homebrew/vendor/bundle/bundler/../ruby/2.6.0/gems/parallel-1.20.0/lib
/usr/local/Homebrew/Library/Homebrew/vendor/bundle/bundler/../ruby/2.6.0/gems/mustache-1.1.1/lib
/usr/local/Homebrew/Library/Homebrew/vendor/bundle/bundler/../ruby/2.6.0/gems/method_source-1.0.0/lib
/usr/local/Homebrew/Library/Homebrew/vendor/bundle/bundler/../ruby/2.6.0/gems/mechanize-2.7.6/lib
/usr/local/Homebrew/Library/Homebrew/vendor/bundle/bundler/../ruby/2.6.0/gems/webrobots-0.1.2/lib
/usr/local/Homebrew/Library/Homebrew/vendor/bundle/bundler/../ruby/2.6.0/gems/ntlm-http-0.1.1/lib
/usr/local/Homebrew/Library/Homebrew/vendor/bundle/bundler/../ruby/2.6.0/gems/nokogiri-1.10.10/lib
/usr/local/Homebrew/Library/Homebrew/vendor/bundle/bundler/../ruby/2.6.0/extensions/universal-darwin-19/2.6.0/nokogiri-1.10.10
/usr/local/Homebrew/Library/Homebrew/vendor/bundle/bundler/../ruby/2.6.0/gems/mini_portile2-2.4.0/lib
/usr/local/Homebrew/Library/Homebrew/vendor/bundle/bundler/../ruby/2.6.0/gems/net-http-persistent-4.0.0/lib
/usr/local/Homebrew/Library/Homebrew/vendor/bundle/bundler/../ruby/2.6.0/gems/net-http-digest_auth-1.4.1/lib
/usr/local/Homebrew/Library/Homebrew/vendor/bundle/bundler/../ruby/2.6.0/gems/mime-types-3.3.1/lib
/usr/local/Homebrew/Library/Homebrew/vendor/bundle/bundler/../ruby/2.6.0/gems/mime-types-data-3.2020.0512/lib
/usr/local/Homebrew/Library/Homebrew/vendor/bundle/bundler/../ruby/2.6.0/gems/http-cookie-1.0.3/lib
/usr/local/Homebrew/Library/Homebrew/vendor/bundle/bundler/../ruby/2.6.0/gems/hpricot-0.8.6/lib
/usr/local/Homebrew/Library/Homebrew/vendor/bundle/bundler/../ruby/2.6.0/extensions/universal-darwin-19/2.6.0/hpricot-0.8.6
/usr/local/Homebrew/Library/Homebrew/vendor/bundle/bundler/../ruby/2.6.0/gems/elftools-1.1.3/lib
/usr/local/Homebrew/Library/Homebrew/vendor/bundle/bundler/../ruby/2.6.0/gems/domain_name-0.5.20190701/lib
/usr/local/Homebrew/Library/Homebrew/vendor/bundle/bundler/../ruby/2.6.0/gems/unf-0.1.4/lib
/usr/local/Homebrew/Library/Homebrew/vendor/bundle/bundler/../ruby/2.6.0/gems/unf_ext-0.0.7.7/lib
/usr/local/Homebrew/Library/Homebrew/vendor/bundle/bundler/../ruby/2.6.0/extensions/universal-darwin-19/2.6.0/unf_ext-0.0.7.7
/usr/local/Homebrew/Library/Homebrew/vendor/bundle/bundler/../ruby/2.6.0/gems/diff-lcs-1.4.4/lib
/usr/local/Homebrew/Library/Homebrew/vendor/bundle/bundler/../ruby/2.6.0/gems/connection_pool-2.2.3/lib
/usr/local/Homebrew/Library/Homebrew/vendor/bundle/bundler/../ruby/2.6.0/gems/commander-4.5.2/lib
/usr/local/Homebrew/Library/Homebrew/vendor/bundle/bundler/../ruby/2.6.0/gems/highline-2.0.3/lib
/usr/local/Homebrew/Library/Homebrew/vendor/bundle/bundler/../ruby/2.6.0/gems/colorize-0.8.1/lib
/usr/local/Homebrew/Library/Homebrew/vendor/bundle/bundler/../ruby/2.6.0/gems/coderay-1.1.3/lib
/usr/local/Homebrew/Library/Homebrew/vendor/bundle/bundler/../ruby/2.6.0/gems/codecov-0.2.12/lib
/usr/local/Homebrew/Library/Homebrew/vendor/bundle/bundler/../ruby/2.6.0/gems/simplecov-0.19.1/lib
/usr/local/Homebrew/Library/Homebrew/vendor/bundle/bundler/../ruby/2.6.0/gems/simplecov-html-0.12.3/lib
/usr/local/Homebrew/Library/Homebrew/vendor/bundle/bundler/../ruby/2.6.0/gems/docile-1.3.2/lib
/usr/local/Homebrew/Library/Homebrew/vendor/bundle/bundler/../ruby/2.6.0/gems/json-2.3.1/lib
/usr/local/Homebrew/Library/Homebrew/vendor/bundle/bundler/../ruby/2.6.0/extensions/universal-darwin-19/2.6.0/json-2.3.1
/usr/local/Homebrew/Library/Homebrew/vendor/bundle/bundler/../ruby/2.6.0/gems/byebug-11.1.3/lib
/usr/local/Homebrew/Library/Homebrew/vendor/bundle/bundler/../ruby/2.6.0/extensions/universal-darwin-19/2.6.0/byebug-11.1.3
/usr/local/Homebrew/Library/Homebrew/vendor/bundle/bundler/
/usr/local/Homebrew/Library/Homebrew/vendor/bundle/bundler/../ruby/2.6.0/gems/bindata-2.4.8/lib
/usr/local/Homebrew/Library/Homebrew/vendor/bundle/bundler/../ruby/2.6.0/gems/ast-2.4.1/lib
/usr/local/Homebrew/Library/Homebrew/vendor/bundle/bundler/../ruby/2.6.0/gems/activesupport-6.0.3.4/lib
/usr/local/Homebrew/Library/Homebrew/vendor/bundle/bundler/../ruby/2.6.0/gems/zeitwerk-2.4.0/lib
/usr/local/Homebrew/Library/Homebrew/vendor/bundle/bundler/../ruby/2.6.0/gems/tzinfo-1.2.7/lib
/usr/local/Homebrew/Library/Homebrew/vendor/bundle/bundler/../ruby/2.6.0/gems/thread_safe-0.3.6/lib
/usr/local/Homebrew/Library/Homebrew/vendor/bundle/bundler/../ruby/2.6.0/gems/minitest-5.14.2/lib
/usr/local/Homebrew/Library/Homebrew/vendor/bundle/bundler/../ruby/2.6.0/gems/i18n-1.8.5/lib
/usr/local/Homebrew/Library/Homebrew/vendor/bundle/bundler/../ruby/2.6.0/gems/concurrent-ruby-1.1.7/lib/concurrent-ruby
/Library/Ruby/Site/2.6.0
/Library/Ruby/Site/2.6.0/universal-darwin20
/Library/Ruby/Site
/System/Library/Frameworks/Ruby.framework/Versions/2.6/usr/lib/ruby/vendor_ruby/2.6.0
/System/Library/Frameworks/Ruby.framework/Versions/2.6/usr/lib/ruby/vendor_ruby/2.6.0/universal-darwin20
/System/Library/Frameworks/Ruby.framework/Versions/2.6/usr/lib/ruby/vendor_ruby
/System/Library/Frameworks/Ruby.framework/Versions/2.6/usr/lib/ruby/2.6.0
/System/Library/Frameworks/Ruby.framework/Versions/2.6/usr/lib/ruby/2.6.0/universal-darwin20
/usr/local/Homebrew/Library/Homebrew
==> Homebrew Version
2.5.10-14-g8561fbf
==> macOS
11.0.1
==> SIP
Enabled
==> Java
11.0.9
==> Homebrew Cask Staging Location
/usr/local/Caskroom
==> Homebrew Cask Taps:
/usr/local/Homebrew/Library/Taps/homebrew/homebrew-cask (3713 casks)
/usr/local/Homebrew/Library/Taps/danielbayley/homebrew-alfred (12 casks)
/usr/local/Homebrew/Library/Taps/peterlewis/homebrew-peterlewis (18 casks)
/usr/local/Homebrew/Library/Taps/homebrew/homebrew-cask-versions (166 casks)
/usr/local/Homebrew/Library/Taps/homebrew/homebrew-cask-fonts (1571 casks)
/usr/local/Homebrew/Library/Taps/homebrew/homebrew-cask-drivers (166 casks)
/usr/local/Homebrew/Library/Taps/adoptopenjdk/homebrew-openjdk (43 casks)
Please note that these warnings are just used to help the Homebrew maintainers
with debugging if you file an issue. If everything you use Homebrew for is
working fine: please don't worry or file an issue; just ignore this. Thanks!

Warning: You are using macOS 11.0.
We do not provide support for this released but not yet supported version.
You will encounter build failures with some formulae.
Please create pull requests instead of asking for help on Homebrew's GitHub,
Discourse, Twitter or any other official channels. You are responsible for
resolving any issues you experience while you are running this
released but not yet supported version.

Output of `brew tap`

adoptopenjdk/openjdk
akx/things
brewsci/bio
danielbayley/alfred
github/gh
gnebbia/kb
homebrew/bundle
homebrew/cask
homebrew/cask-drivers
homebrew/cask-fonts
homebrew/cask-versions
homebrew/core
homebrew/services
koekeishiya/formulae
peterlewis/peterlewis
powershell/tap
schollz/tap
vitorgalvao/tiny-scripts