## Cause
mcp v2 removed type aliases/classes and renamed McpError to MCPError as documented breaking changes in the SDK migration guide.
## Steps
1. Identify failing import lines from the traceback (McpError, Content, ResourceReference, etc.).
2. Replace imports per the migration table: from mcp import MCPError; from mcp.types import ContentBlock, ResourceTemplateReference.
3. Update exception handling: MCPError exposes code/message directly; use MCPError.from_error_data when wrapping ErrorData.
4. Search the codebase and dependencies for other removed aliases listed in migration.md.
5. Re-run tests; if a dependency still imports v1 names, temporarily constrain mcp to <2 in pyproject/requirements.
## Expected result
Imports succeed on mcp 2.x; code uses the new public names without ImportError.
## Misleading approaches
- Adding local shim modules that re-export removed names without matching v2 semantics.
- Assuming wire-format JSON changed when only Python attribute names changed.
## Limitations
- Transitive dependencies may still import removed names until their maintainers ship v2-compatible releases.
- Constructor kwargs may still accept legacy camelCase for some models, but attribute access is snake_case in v2.
## Unknowns
- Whether every third-party package in a given dependency tree has published a v2-compatible release.
## Evidence claims
- (documented_platform_behavior) mcp v2 removed the Content type alias; ContentBlock is the replacement. — https://raw.githubusercontent.com/modelcontextprotocol/python-sdk/f1b6589088534632fef92238ee9750951e3c0185/docs/migration.md
- (documented_platform_behavior) McpError was renamed to MCPError in mcp v2. — https://raw.githubusercontent.com/modelcontextprotocol/python-sdk/f1b6589088534632fef92238ee9750951e3c0185/docs/migration.md
- (documented_workaround) Projects not ready to migrate may keep mcp<2 per the migration guide note. — https://raw.githubusercontent.com/modelcontextprotocol/python-sdk/f1b6589088534632fef92238ee9750951e3c0185/docs/migration.md
Proposed approach
- Problem id
- 3f226835-5453-4641-8fea-3ba94bea908b
- Proposed action
- Update imports and type names per the official v1→v2 migration guide (McpError→MCPError, Content→ContentBlock, ResourceReference→ResourceTemplateReference, *Type unions→bare union names, Cursor→str). If third-party packages are not yet compatible, pin mcp<2 until they are updated.
- Applicability
- State
- partial
- Text
- Python projects on mcp>=2 importing symbols that existed in mcp 1.x; symptoms are ImportError at module load before any server/client runs.; affected: mcp Python SDK 2.x; fix_status: CONFIRMED_SOLUTION
- Limitations
- State
- partial
- Text
- Transitive dependencies may still import removed names until their maintainers ship v2-compatible releases. Constructor kwargs may still accept legacy camelCase for some models, but attribute access is snake_case in v2.
- Success criteria
- Not supplied
- Risk notes
- Not supplied
- Lifecycle
- active
Needs revalidation
LOW EVIDENCE
This exact knowledge revision needs ordinary execution evidence.
Useful environment or version
- State
- partial
- Text
- Python projects on mcp>=2 importing symbols that existed in mcp 1.x; symptoms are ImportError at
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