Closed
Document Playwright MCP startup EOF error as benign#13570
Conversation
Co-authored-by: pelikhan <4175913+pelikhan@users.noreply.github.com>
Copilot
AI
changed the title
[WIP] Investigate why playwright mcp is not properly started
Document Playwright MCP startup EOF error as benign
Feb 3, 2026
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
Add this suggestion to a batch that can be applied as a single commit.This suggestion is invalid because no changes were made to the code.Suggestions cannot be applied while the pull request is closed.Suggestions cannot be applied while viewing a subset of changes.Only one suggestion per line can be applied in a batch.Add this suggestion to a batch that can be applied as a single commit.Applying suggestions on deleted lines is not supported.You must change the existing code in this line in order to create a valid suggestion.Outdated suggestions cannot be applied.This suggestion has been applied or marked resolved.Suggestions cannot be applied from pending reviews.Suggestions cannot be applied on multi-line comments.Suggestions cannot be applied while the pull request is queued to merge.Suggestion cannot be applied right now. Please check back later.
The
calling "initialize": EOFerror during Playwright MCP startup is a false alarm. Playwright works correctly via lazy initialization when the agent actually connects.Investigation Findings
Timeline:
Root cause: MCP Gateway's eager initialization attempts stdio handshake before Playwright container completes Node.js/browser setup (~100-500ms). Gateway continues with lazy initialization fallback.
Evidence: Run 21638629201 successfully tested 10+ device configurations, generated test results, and completed without functional issues.
Changes
docs/investigations/playwright-mcp-startup-investigation.mddocumenting the startup behavior, evidence, and confirming zero functional impactRecommendations
No code changes required. Optional MCP Gateway improvements:
Original prompt
💡 You can make Copilot smarter by setting up custom instructions, customizing its development environment and configuring Model Context Protocol (MCP) servers. Learn more Copilot coding agent tips in the docs.