dotnet/runtime · error · RuntimeError

Pass only one tiering option.

Error message

Pass only one tiering option.

What it means

Raised in SuperPMICollection.__init__ (superpmi.py:725-726) when both --tiered_compilation and --tiered_pgo are passed to the `collect` subcommand. The flags are treated as mutually exclusive because --tiered_pgo already sets DOTNET_TieredCompilation=1 in addition to DOTNET_TieredPGO=1, so specifying both is redundant and ambiguous. This is a runtime guard, not an argparse mutually_exclusive_group, so argparse will not catch it earlier.

Source

Thrown at src/coreclr/scripts/superpmi.py:726

            self.corerun = os.path.join(self.core_root, self.corerun_tool_name)

        if coreclr_args.crossgen2:
            self.corerun = os.path.join(self.core_root, self.corerun_tool_name)

        if coreclr_args.pmi or coreclr_args.crossgen2:
            self.assemblies = coreclr_args.assemblies
            self.exclude = coreclr_args.exclude
            if coreclr_args.tiered_compilation or coreclr_args.tiered_pgo:
               raise RuntimeError("Tiering options have no effect for pmi or crossgen2 collections.")

        if coreclr_args.nativeaot:
            self.ilc_rsps = coreclr_args.ilc_rsps
            self.exclude = coreclr_args.exclude
            if coreclr_args.tiered_compilation or coreclr_args.tiered_pgo:
                raise RuntimeError("Tiering options have no effect for nativeaot collections.")

        if coreclr_args.tiered_compilation and coreclr_args.tiered_pgo:
            raise RuntimeError("Pass only one tiering option.")

        self.coreclr_args = coreclr_args

        self.temp_location = None

        # Pathname for a temporary .MCL file used for noticing SuperPMI replay failures against base MCH.
        self.base_fail_mcl_file = None

        # The base .MCH file path
        self.base_mch_file = None

        # Final .MCH file path
        if self.coreclr_args.output_mch_path is not None:
            self.final_mch_file = os.path.abspath(self.coreclr_args.output_mch_path)
            final_mch_dir = os.path.dirname(self.final_mch_file)
            if not os.path.isdir(final_mch_dir):
                os.makedirs(final_mch_dir)
        else:

View on GitHub (pinned to 290d5ab72c)

Solutions

1. Remove --tiered_compilation and keep only --tiered_pgo (it enables both DOTNET_TieredCompilation=1 and DOTNET_TieredPGO=1).
2. If you only want tiered compilation without PGO, drop --tiered_pgo and keep --tiered_compilation alone.
3. Fix the script/matrix that assembles the CLI args to treat the two flags as mutually exclusive.

Example fix

// before
superpmi.py collect --crossgen2 -assemblies Foo --tiered_compilation --tiered_pgo
// after
superpmi.py collect --crossgen2 -assemblies Foo --tiered_pgo

# Before invoking superpmi collect, reject the conflicting combination
import sys
tiered_compilation = '--tiered_compilation' in sys.argv
tiered_pgo = '--tiered_pgo' in sys.argv
if tiered_compilation and tiered_pgo:
    raise SystemExit('Use only one of --tiered_compilation / --tiered_pgo (tiered_pgo implies tiered_compilation).')
# ...then launch superpmi.py

When it happens

Trigger: Running `superpmi.py collect ... --tiered_compilation --tiered_pgo ...`. Both are `store_true` flags with no argparse choices restriction, so the command parses successfully and the check in __init__ is what rejects it.

Common situations: Starting from a tiered-compilation collection command and appending --tiered_pgo to enable PGO without dropping the first flag; matrix/CI scripts that toggle the two flags from independent variables and accidentally set both to true.

Related errors

• Invalid summary_type: {coreclr_args.summary_type}
• Specified -base_jit_path does not point to a file
• Tiering options have no effect for pmi or crossgen2 collecti
• Tiering options have no effect for nativeaot collections.
• Expected a '.ilc.rsp' file for nativeaot, but got {original_

AI-assisted analysis of dotnet/runtime@290d5ab72c (2026-08-06). Data as JSON: /api/errors/b5957df24715acf7. Report an issue: GitHub.