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Public story · 2026-08-26 · high
Version 2.0.0 renamed a core import without a shim, so pip install mcp started throwing ModuleNotFoundError in servers that never touched their own code.
Why now: The backport went up August 26.
The Model Context Protocol's Python SDK released a fix for a break its previous release caused. Version 2.0.1, posted August 26, exists because SDK 2.0.0 moved mcp.server.fastmcp.* to mcp.server.mcpserver.* and renamed the FastMCP class to MCPServer. It left no backward-compatible import path behind.
Anyone who ran pip install mcp after that got a ModuleNotFoundError in their server code. Nothing in the error pointed back to the SDK, so maintainers had no way to know it wasn't a bug in their own project. The release notes say the backport exists "due to a lot of people running into this error and making issues on other repos about it." The confusion had spread to maintainers who had nothing to do with the SDK.
If you maintain an MCP server, you've got two ways out. Pin mcp>=1.28,<2 to stay on the old import paths, or update your code to mcp.server.mcpserver and swap FastMCP for MCPServer. The SDK didn't touch decorator arguments or handler signatures, so the fix is a find-and-replace on imports and one constructor name, not a rewrite.
Each link below shares sources, entities, or timing with this story.
FastMCP deprecates MCPServer / Shared entities / Same source domain / Shared topic / Earlier coverage
Linked by a graph relationship (FastMCP deprecates MCPServer); both cover FastMCP, MCP Python SDK, MCPServer, SDK; reported by the same outlet (github.com).
PrefectHQ released FastMCP / Shared entity: FastMCP / Same source domain / Shared topic / Earlier coverage
Linked by a graph relationship (PrefectHQ released FastMCP); both cover FastMCP; reported by the same outlet (github.com).
FastMCP deprecates MCPServer / Shared entities / Shared topic / Earlier coverage
Linked by a graph relationship (FastMCP deprecates MCPServer); both cover FastMCP, MCPServer; overlapping topics (call, server).
Shared entities / Same source domain / Shared topic / Earlier coverage
Both cover August, SDK; reported by the same outlet (github.com); overlapping topics (call, change, server).
Both cover August, SDK; reported by the same outlet (github.com); overlapping topics (august, change).
Both cover August, SDK; reported by the same outlet (github.com); overlapping topics (august, call).
FastMCP deprecates MCPServer / Shared entities / Earlier coverage
Linked by a graph relationship (FastMCP deprecates MCPServer); both cover McpServer, SDK; earlier McpServer coverage from 2026-07-01.
Shared entity: August / Same source domain / Shared topic / Tension
Both cover August; reported by the same outlet (github.com); overlapping topics (august, call, server).