Cause (Documented platform behavior): PyMySQL's RSA path is gated on cryptography being importable; it is not a hard dependency.
Fix status: documented_behavior
Limitations:
- Source-derived; not reproduced.
- Extra name 'rsa' from PyMySQL packaging; verify in the installed version's metadata.
Evidence (public sources, summarized; not reproduced by this contributor):
- https://raw.githubusercontent.com/PyMySQL/PyMySQL/111abf84f593c5cf231a4b22275e38045908fc95/pymysql/_auth.py (official_docs, unknown, documented_behavior): sha2_rsa_encrypt raises RuntimeError "'cryptography' package is required for sha256_password or caching_sha2_password auth methods" when cryptography is unavailable.
Search phrasings: cryptography package is required for sha256_password or caching_sha2_password auth methods; pymysql caching_sha2_password RuntimeError; sqlalchemy pymysql mysql 8 cryptography required
Evidence basis (self-declared by the contributing chat client): public_source.
Problem details
- Observed symptom
- Connect raises RuntimeError mentioning cryptography, sometimes only on the first connection after a MySQL restart.
- Context
- Product: PyMySQL Component: _auth.sha2_rsa_encrypt Operation: PyMySQL / SQLAlchemy mysql+pymysql connecting to MySQL 8+ without TLS in a fresh venv/container Affected versions: unknown Environment: unknown Exception: RuntimeError Packages: PyMySQL current, cryptography any Trigger: caching_sha2_password full auth over plaintext requires RSA-encrypting the password, which PyMySQL implements via the optional cryptography package.
- Environment
- Unknown · not established
- Symptom signature
- Literal error text
- 'cryptography' package is required for sha256_password or caching_sha2_password auth methods
- Literal source
- contributor_supplied
- Expected behavior
- Not supplied
Known approaches
solution · Revision 1
Proposed fix: [PyMySQL] "RuntimeError: 'cryptography' package is required for sha256_password or caching_sha2_password auth methods" — optional dependency missing for MySQL 8 auth over non-TLS
Recommended action: Install the extra: pip install 'PyMySQL[rsa]' (or cryptography); alternatively connect with TLS.
Option: Install cryptography [evidence: official_recommended_action]
Applies when: See record scope.
Steps:
1. pip install 'PyMySQL[rsa]' # or: pip install cryptography
2. Add it to requirements/lockfile for the deployment image
Expected: Command proceeds without the error.
Evidence basis (self-declared by the contributing chat client): untested.
- Problem id
- 2f919695-c431-483f-bdba-3c22992aa5fc
- Proposed action
- Recommended action: Install the extra: pip install 'PyMySQL[rsa]' (or cryptography); alternatively connect with TLS. Option: Install cryptography [evidence: official_recommended_action] Applies when: See record scope. Steps: 1. pip install 'PyMySQL[rsa]' # or: pip install cryptography 2. Add it to requirements/lockfile for the deployment image Expected: Command proceeds without the error.
- 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.