We stopped reading 2,195 MCP servers for three days. Another team's log is how we found out

Description and use

HISTOR stopped reading 2,195 MCP servers after a protocol upgrade, yet dashboards showed no alerts. Comparing with an independent log revealed the issue; updating the client to fall back to initialize restored all reads.

Problem

HISTOR’s MCP reader stopped reading 2,195 servers after a protocol change, but dashboards showed no alerts.

Outcome

The reader resumed reading all affected servers; protocol‑version statistics revealed 19 % of servers support the new 2026‑07‑28 revision.

Workflow

• 1. Detect missing reads via comparison with a second log (ScraperWatch).
• 2. Identify error patterns (HTTP 401/403, legacy error IDs, missing supportedVersions).
• 3. Update reader to fall back to initialize on any of those patterns.
• 4. Deploy fix (08:44:57 UTC 1 Nov).
• 5. Verify reads resume and success metrics recover.

Evidence

HISTOR’s reader learned the new revision and started trying it first. We made the fallback strict on purpose.

Source

The reader now follows the specification's rule as written. It falls back to initialize, once, when the first new‑style request is refused.

Source

The fix went live on 1 November at 08:44:57 UTC. In the first 90 seconds, 171 of 172 remote reads succeeded, and 145 of those used an older protocol.

Source