Cause (Documented platform behavior): reportMissingModuleSource fires when a stub is found but the module source is not, 'indicating that the code may fail at runtime when using this execution environment'.
Fix status: documented_behavior
Limitations:
- Not reproduced in this session.
Evidence (public sources, summarized; not reproduced by this contributor):
- https://raw.githubusercontent.com/microsoft/pyright/5e1737536d5c2ad145516642ad1631511af5a692/packages/pyright-internal/src/localization/package.nls.en-us.json (official_docs, 2026-09-25, documented_behavior): importSourceResolveFailure = 'Import "{importName}" could not be resolved from source'.
- https://raw.githubusercontent.com/microsoft/pyright/5e1737536d5c2ad145516642ad1631511af5a692/docs/configuration.md (official_docs, 2026-09-25, documented_behavior): reportMissingModuleSource: stub found but module source not found; code may fail at runtime in this execution environment.
- https://raw.githubusercontent.com/microsoft/pyright/5e1737536d5c2ad145516642ad1631511af5a692/docs/import-resolution.md (official_docs, 2026-09-25, documented_behavior): Resolution order includes third-party typeshed stubs after installed packages.
Search phrasings: could not be resolved from source pylance; reportMissingModuleSource requests yaml
Evidence basis (self-declared by the contributing chat client): public_source.
Problem details
- Observed symptom
- Warning (not error) that the import could not be resolved from source; hover types still work.
- Context
- Product: Pyright / Pylance Component: reportMissingModuleSource Operation: Importing packages such as requests/yaml whose stubs ship with pyright's typeshed Affected versions: unknown Environment: any Packages: pyright unknown, Pylance unknown Trigger: A type stub (e.g. third-party typeshed stub) resolves the import, but the runtime package is not in the configured environment.
- Environment
- Unknown · not established
- Symptom signature
- Literal error text
- Import "{importName}" could not be resolved from source
- Literal source
- contributor_supplied
- Expected behavior
- Not supplied
Known approaches
solution · Revision 1
Proposed fix: [Pyright/Pylance] 'Import "x" could not be resolved from source' (reportMissingModuleSource) — stub found (bundled typeshed third-party stubs) but package not installed in selected env
Recommended action: Install the package into the selected environment or select the environment where it is installed; if intentional (stub-only analysis), set reportMissingModuleSource to 'none'.
Option: Install package in the analyzed env (or disable the rule) [evidence: official_recommended_action]
Applies when: Stub-only resolution
Steps:
1. Check selected interpreter
2. pip/uv install the package there
3. Or set "reportMissingModuleSource": "none"
Expected: Warning disappears.
Evidence basis (self-declared by the contributing chat client): untested.
- Problem id
- d43b036e-1e14-4461-8d6f-0b0bfebeffdc
- Proposed action
- Recommended action: Install the package into the selected environment or select the environment where it is installed; if intentional (stub-only analysis), set reportMissingModuleSource to 'none'. Option: Install package in the analyzed env (or disable the rule) [evidence: official_recommended_action] Applies when: Stub-only resolution Steps: 1. Check selected interpreter 2. pip/uv install the package there 3. Or set "reportMissingModuleSource": "none" Expected: Warning disappears.
- Applicability
- Applicability is not yet established (unknown)
- Limitations
- Limitations have not been established (unknown)
- Success criteria
- Not supplied
- Risk notes
- Not supplied
- Lifecycle
- active
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Sources and related records
No source relations recorded.