$> spack mirror add E4S https://cache.e4s.io
$> spack buildcache keys -it

$> spack --debug --stacktrace install libpressio
...
lib/spack/spack/util/web.py:392 ==> [2022-11-23-10:43:06.080448] Checking existence of https://cache.e4s.io/build_cache/index.json
lib/spack/spack/binary_distribution.py:476 ==> [2022-11-23-10:43:06.908180] Cached index for https://cache.e4s.io already up to date
lib/spack/spack/util/web.py:392 ==> [2022-11-23-10:43:06.908939] Checking existence of https://mirror.spack.io/build_cache/index.json
lib/spack/spack/util/web.py:441 ==> [2022-11-23-10:43:06.938828] Failure reading URL: Download failed: HTTP Error 404: Not Found
lib/spack/spack/database.py:389 ==> [2022-11-23-10:43:06.940681] DATABASE LOCK TIMEOUT: 3s
lib/spack/spack/database.py:395 ==> [2022-11-23-10:43:06.940935] PACKAGE LOCK TIMEOUT: No timeout
...
lib/spack/spack/config.py:1002 ==> [2022-11-23-10:43:32.962367] Reading config from file /root/.spack/linux/compilers.yaml
lib/spack/spack/cmd/install.py:451 ==> [2022-11-23-10:44:06.489322] UnknownPackageError: Package 'netcdf' not found.
    You may need to run 'spack clean -m'.
lib/spack/spack/main.py:1003 ==> [2022-11-23-10:44:06.489528] UnknownPackageError: Package 'netcdf' not found.
    You may need to run 'spack clean -m'.
lib/spack/spack/error.py:54 ==> [2022-11-23-10:44:06.489740] Error: Package 'netcdf' not found.
You may need to run 'spack clean -m'.
Traceback (most recent call last):
  File "/spack/lib/spack/spack/repo.py", line 1229, in get_pkg_class
    module = importlib.import_module(fullname)
  File "/usr/lib/python3.8/importlib/__init__.py", line 127, in import_module
    return _bootstrap._gcd_import(name[level:], package, level)
  File "<frozen importlib._bootstrap>", line 1014, in _gcd_import
  File "<frozen importlib._bootstrap>", line 991, in _find_and_load
  File "<frozen importlib._bootstrap>", line 973, in _find_and_load_unlocked
ModuleNotFoundError: No module named 'spack.pkg.builtin.netcdf'

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/spack/lib/spack/spack/main.py", line 1000, in main
    return _main(argv)
  File "/spack/lib/spack/spack/main.py", line 955, in _main
    return finish_parse_and_run(parser, cmd_name, env_format_error)
  File "/spack/lib/spack/spack/main.py", line 983, in finish_parse_and_run
    return _invoke_command(command, parser, args, unknown)
  File "/spack/lib/spack/spack/main.py", line 632, in _invoke_command
    return_val = command(parser, args)
  File "/spack/lib/spack/spack/cmd/install.py", line 531, in install
    abstract_specs, concrete_specs = specs_from_cli(args, install_kwargs, reporter)
  File "/spack/lib/spack/spack/cmd/install.py", line 447, in specs_from_cli
    concrete_specs = spack.cmd.parse_specs(
  File "/spack/lib/spack/spack/cmd/__init__.py", line 227, in parse_specs
    spec.concretize(tests=tests)  # implies normalize
  File "/spack/lib/spack/spack/spec.py", line 2978, in concretize
    self._new_concretize(tests)
  File "/spack/lib/spack/spack/spec.py", line 2953, in _new_concretize
    result = solver.solve([self], tests=tests)
  File "/spack/lib/spack/spack/solver/asp.py", line 2435, in solve
    result, _, _ = self.driver.solve(setup, specs, reuse=reusable_specs, output=output)
  File "/spack/lib/spack/spack/solver/asp.py", line 625, in solve
    setup.setup(self, specs, reuse=reuse)
  File "/spack/lib/spack/spack/solver/asp.py", line 1989, in setup
    self._facts_from_concrete_spec(reusable_spec, possible)
  File "/spack/lib/spack/spack/solver/asp.py", line 1897, in _facts_from_concrete_spec
    self.impose(h, spec, body=True)
  File "/spack/lib/spack/spack/solver/asp.py", line 1090, in impose
    imposed_constraints = self.spec_clauses(imposed_spec, body=body, required_from=name)
  File "/spack/lib/spack/spack/solver/asp.py", line 1313, in spec_clauses
    clauses = self._spec_clauses(*args, **kwargs)
  File "/spack/lib/spack/spack/solver/asp.py", line 1478, in _spec_clauses
    for virtual in dep.package.virtuals_provided:
  File "/spack/lib/spack/spack/spec.py", line 1638, in package
    self._package = spack.repo.path.get(self)
  File "/spack/lib/spack/spack/repo.py", line 849, in get
    return self.repo_for_pkg(spec).get(spec)
  File "/spack/lib/spack/spack/repo.py", line 1042, in get
    package_class = self.get_pkg_class(spec.name)
  File "/spack/lib/spack/spack/repo.py", line 1231, in get_pkg_class
    raise UnknownPackageError(pkg_name)
spack.repo.UnknownPackageError: Package 'netcdf' not found.
    You may need to run 'spack clean -m'.