fix(pool): add useH2c option support for multiple connections #4738
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The Pool class was not passing the useH2c option to buildConnector
and kOptions, causing HTTPParserError when using Agent with useH2c
and connections > 1.
This fix ensures that:
- useH2c is extracted from constructor parameters
- useH2c is passed to buildConnector for proper connection setup
- useH2c is included in kOptions for client instances
Fixes issue with h2c (HTTP/2 Cleartext) failing on second connection
when Pool creates multiple Client instances.
Before: connections > 1 with useH2c caused HTTP/1.1 parser to receive
HTTP/2 binary frames, resulting in protocol mismatch error
After: All connections properly use HTTP/2 cleartext protocol
Fixes nodejs#4737
mcollina
requested changes
Jan 19, 2026
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mcollina
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mcollina
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Thanks for opening a PR! Can you please add a unit test?
Codecov Report✅ All modified and coverable lines are covered by tests. Additional details and impacted files@@ Coverage Diff @@
## main #4738 +/- ##
==========================================
- Coverage 92.89% 92.88% -0.01%
==========================================
Files 109 109
Lines 33886 33888 +2
==========================================
Hits 31478 31478
- Misses 2408 2410 +2 ☔ View full report in Codecov by Sentry. 🚀 New features to boost your workflow:
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This relates to...
#4737
Rationale
The Pool class was not passing the useH2c option to buildConnector and kOptions, causing HTTPParserError when using Agent with useH2c and connections > 1.
Changes
This fix ensures that:
Features
N/A
Bug Fixes
Fixes issue with h2c (HTTP/2 Cleartext) failing on second connection when Pool creates multiple Client instances.
Breaking Changes and Deprecations
Before: connections > 1 with useH2c caused HTTP/1.1 parser to receive
HTTP/2 binary frames, resulting in protocol mismatch error
After: All connections properly use HTTP/2 cleartext protocol
Status