The Fix
Resolves a warning that occurs when using built-in functions for JSON serialization in psycopg. It ensures that no warnings are raised when these functions are used.
Based on closed psycopg/psycopg issue #1165 · PR/commit linked
Production note: Most teams hit this during upgrades or environment changes. Roll out with a canary and smoke critical endpoints (health, OpenAPI/docs) before 100%.
@@ -43,6 +43,13 @@ Psycopg 3.3.0 (unreleased)
+Psycopg 3.2.11 (unreleased)
+^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
In [4]: import psycopg
In [5]: import orjson
# this causes no warning
In [6]: psycopg.types.json.set_json_dumps(orjson.dumps)
In [7]: conn = psycopg.connect()
# This causes a warning
In [8]: psycopg.types.json.set_json_dumps(orjson.dumps, conn)
/home/piro/dev/psycopg3/psycopg/build/__editable__.psycopg-3.3.0.dev1-py3-none-any/psycopg/types/json.py:165: RuntimeWarning: function <built-in function dumps> has no __code__ or __closure__.
warn(f"function {f} has no __code__ or __closure__.", RuntimeWarning)
Re-run the minimal reproduction on your broken version, then apply the fix and re-run.
Option A — Apply the official fix\nResolves a warning that occurs when using built-in functions for JSON serialization in psycopg. It ensures that no warnings are raised when these functions are used.\nWhen NOT to use: This fix should not be used if the built-in functions are not intended for JSON serialization.\n\n
Why This Fix Works in Production
- Trigger: [json] new warning emited by a recent change in types/json.py with orjson
- Mechanism: The warning is caused by using built-in functions for JSON serialization without proper handling in psycopg
- If left unfixed, the same config can fail only in production (env differences), causing startup failures or partial feature outages.
Why This Breaks in Prod
- The warning is caused by using built-in functions for JSON serialization without proper handling in psycopg
- Production symptom (often without a traceback): [json] new warning emited by a recent change in types/json.py with orjson
Proof / Evidence
- GitHub issue: #1165
- Fix PR: https://github.com/psycopg/psycopg/pull/1166
- Reproduced locally: No (not executed)
- Last verified: 2026-02-09
- Confidence: 0.70
- Did this fix it?: Yes (upstream fix exists)
- Own content ratio: 0.67
Discussion
High-signal excerpts from the issue thread (symptoms, repros, edge-cases).
“Thank you very much for the follow-up. I think that the fix in #1166 will solve the problem. In the meantime you can work around…”
“Hi, Thank you for the quick response ! My real case is slighltly more intricated and involve SQLAlchemy as well”
“Hello, thank you for the report! Yes, you are correct and this comes from #1108 My understanding from the behaviour I have tested and the…”
Failure Signature (Search String)
- [json] new warning emited by a recent change in types/json.py with orjson
Copy-friendly signature
Failure Signature
-----------------
[json] new warning emited by a recent change in types/json.py with orjson
Error Message
Signature-only (no traceback captured)
Error Message
-------------
[json] new warning emited by a recent change in types/json.py with orjson
Minimal Reproduction
In [4]: import psycopg
In [5]: import orjson
# this causes no warning
In [6]: psycopg.types.json.set_json_dumps(orjson.dumps)
In [7]: conn = psycopg.connect()
# This causes a warning
In [8]: psycopg.types.json.set_json_dumps(orjson.dumps, conn)
/home/piro/dev/psycopg3/psycopg/build/__editable__.psycopg-3.3.0.dev1-py3-none-any/psycopg/types/json.py:165: RuntimeWarning: function <built-in function dumps> has no __code__ or __closure__.
warn(f"function {f} has no __code__ or __closure__.", RuntimeWarning)
What Broke
Users experience warnings when using orjson with psycopg for JSON serialization.
Why It Broke
The warning is caused by using built-in functions for JSON serialization without proper handling in psycopg
Fix Options (Details)
Option A — Apply the official fix
Resolves a warning that occurs when using built-in functions for JSON serialization in psycopg. It ensures that no warnings are raised when these functions are used.
Fix reference: https://github.com/psycopg/psycopg/pull/1166
Last verified: 2026-02-09. Validate in your environment.
When NOT to Use This Fix
- This fix should not be used if the built-in functions are not intended for JSON serialization.
Verify Fix
Re-run the minimal reproduction on your broken version, then apply the fix and re-run.
Did This Fix Work in Your Case?
Quick signal helps us prioritize which fixes to verify and improve.
Prevention
- Capture the exact failing error string in logs and tests so you can reproduce via a minimal script.
- Pin production dependencies and upgrade only with a reproducible test that hits the failing path.
Related Issues
No related fixes found.
Sources
We don’t republish the full GitHub discussion text. Use the links above for context.