fix: make UrlElicitationRequiredError pickle-safe#2471
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Christian-Sidak wants to merge 2 commits intomodelcontextprotocol:mainfrom
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fix: make UrlElicitationRequiredError pickle-safe#2471Christian-Sidak wants to merge 2 commits intomodelcontextprotocol:mainfrom
Christian-Sidak wants to merge 2 commits intomodelcontextprotocol:mainfrom
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Pickle reconstructs exceptions by calling cls(*args). Since UrlElicitationRequiredError inherits MCPError's args=(code, message, data), it fails on restore because its __init__ expects (elicitations, message). Adding __reduce__ to return (from_error, (self.error,)) ensures pickle uses the existing from_error classmethod to reconstruct the object correctly. Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
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Closing -- duplicate of #2439 which already fixes this. |
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Summary
UrlElicitationRequiredErrorfails to unpickle because Python reconstructs exceptions by callingcls(*self.args). Since it inherits fromMCPError, itsargscontain(code, message, data), but its__init__expects(elicitations, message)— causing aTypeErroron restore.The fix adds
__reduce__toUrlElicitationRequiredError, directing pickle to use the existingfrom_errorclassmethod for reconstruction, which correctly rebuilds the full object fromErrorData.Changes
src/mcp/shared/exceptions.py: add__reduce__toUrlElicitationRequiredErrortests/shared/test_exceptions.py: add pickle round-trip tests for bothMCPErrorandUrlElicitationRequiredErrorFixes #2431