Why can't I run an MCP server behind a load balancer?

The MCP spec requires a stateful initialization handshake. Session state is tied to a specific server instance, so a standard round-robin load balancer routes requests to the wrong instance and breaks the session.

How do I scale MCP servers horizontally?

Current workarounds are sticky sessions (fragile on restarts) or a shared Redis session store. The MCP 2026-07-28 RC makes the protocol stateless, enabling true horizontal scaling.

What is the MCP stateless spec RC?

The 2026-07-28 MCP release candidate removes the mandatory init handshake, making each request self-contained. Servers can then run behind any plain load balancer without sticky sessions.

← Back to dashboard

clawsmith.com/signal/mcp-stateful-sessions-block-horizontal-scaling

⚠ IssueUnderservedai_agent_mcpLive

MCP stateful sessions force sticky load balancers and block horizontal scaling

The MCP spec requires a stateful initialization handshake. Putting an MCP server behind a standard load balancer breaks sessions because requests land on different instances. Operators must use sticky sessions (which fail on restart) or a shared Redis session store (adding a SPOF). This made horizontal scaling and Kubernetes-native deploys impossible without workarounds. The MCP spec team opened SEP-1442 in Sept 2025 to make the protocol stateless by default, which became the headline change in the 2026-07-28 RC.

Product Idea from this Signal

A CLI tool that wraps stateful MCP servers and externalizes their session state so they run behind standard round-robin load balancers without sticky routing

173 ▲

Existing MCP servers built on the 2025-11-05 stateful spec rely on in-process session state that breaks under horizontal scaling because round-robin load balancers route requests to the wrong instance. The MCP 2026-07-28 RC removes the stateful handshake at the protocol level, leaving every existing stateful MCP server needing a migration path. This tool wraps any existing MCP server binary, intercepts session lifecycle calls, externalizes session state to Redis or a compatible KV store, and re-exposes the server as a stateless-compatible endpoint that runs behind any vanilla AWS ALB or Cloudflare load balancer with zero sticky-session config.

mcpai-agentsdeveloper-toolsinfrastructureload-balancingsession-managementmigration

Competitive31 leadsView Opportunity →