[Bug] Anthropic API Error: PNG screenshots sent with incorrect image/jpeg MIME type

Found 3 possible duplicate issues:

1. https://github.com/anthropics/claude-code/issues/3175
2. https://github.com/anthropics/claude-code/issues/9938
3. https://github.com/anthropics/claude-code/issues/988

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🤖 Generated with Claude Code

I have the same problem.

<img width="1917" height="366" alt="Image" src="https://github.com/user-attachments/assets/2ff77fae-f1a9-4ec9-bb01-0d7739f284f4" />

How do I continue working with Claude Code further in this case?

<img width="1915" height="459" alt="Image" src="https://github.com/user-attachments/assets/a81c5fce-b7fc-4214-b40b-046c3865c41b" />

+1

Workaround: PreToolUse Hook to Block PNG Screenshots

The root cause is a Playwright MCP bug where PNG screenshots are incorrectly declared with image/jpeg media type, causing API rejections.

Solution: Use a PreToolUse hook to block non-JPEG screenshot requests and force Claude to use JPEG format.

Setup

1. Create .claude/hooks/playwright-screenshot-guard.py:

#!/usr/bin/env python3
import sys, json

def main():
    input_data = json.load(sys.stdin)
    tool_name = input_data.get("tool_name", "")
    tool_input = input_data.get("tool_input", {})

    # Block non-JPEG screenshots
    if "browser_take_screenshot" in tool_name:
        screenshot_type = tool_input.get("type", "png")
        
        if screenshot_type != "jpeg":
            print("🚫 BLOCKED: Playwright screenshot must use JPEG format", file=sys.stderr)
            print("", file=sys.stderr)
            print("Playwright MCP bug: PNG screenshots fail with media type mismatch", file=sys.stderr)
            print("Solution: Set type='jpeg' in browser_take_screenshot", file=sys.stderr)
            print(f"Current: type='{screenshot_type}' ❌", file=sys.stderr)
            print("Required: type='jpeg' ✅", file=sys.stderr)
            sys.exit(2)  # Block tool execution
    
    sys.exit(0)  # Allow

if __name__ == "__main__":
    main()

1. Make executable: chmod +x .claude/hooks/playwright-screenshot-guard.py

1. Add to .claude/settings.json:

{
  "hooks": {
    "PreToolUse": [
      {
        "matcher": "mcp__playwright__browser_take_screenshot",
        "hooks": [
          {
            "type": "command",
            "command": ".claude/hooks/playwright-screenshot-guard.py",
            "timeout": 5000
          }
        ]
      }
    ]
  }
}

Result: Claude will be blocked from taking PNG screenshots and forced to use type='jpeg', which works correctly with the Anthropic API.

Tested and verified - no more media type mismatch errors.

## Workaround: PreToolUse Hook to Block PNG Screenshots The root cause is a Playwright MCP bug where PNG screenshots are incorrectly declared with image/jpeg media type, causing API rejections. Solution: Use a PreToolUse hook to block non-JPEG screenshot requests and force Claude to use JPEG format. ### Setup 1. Create .claude/hooks/playwright-screenshot-guard.py: #!/usr/bin/env python3 import sys, json def main(): input_data = json.load(sys.stdin) tool_name = input_data.get("tool_name", "") tool_input = input_data.get("tool_input", {}) # Block non-JPEG screenshots if "browser_take_screenshot" in tool_name: screenshot_type = tool_input.get("type", "png") if screenshot_type != "jpeg": print("🚫 BLOCKED: Playwright screenshot must use JPEG format", file=sys.stderr) print("", file=sys.stderr) print("Playwright MCP bug: PNG screenshots fail with media type mismatch", file=sys.stderr) print("Solution: Set type='jpeg' in browser_take_screenshot", file=sys.stderr) print(f"Current: type='{screenshot_type}' ❌", file=sys.stderr) print("Required: type='jpeg' ✅", file=sys.stderr) sys.exit(2) # Block tool execution sys.exit(0) # Allow if __name__ == "__main__": main() 2. Make executable: chmod +x .claude/hooks/playwright-screenshot-guard.py 3. Add to .claude/settings.json: { "hooks": { "PreToolUse": [ { "matcher": "mcp__playwright__browser_take_screenshot", "hooks": [ { "type": "command", "command": ".claude/hooks/playwright-screenshot-guard.py", "timeout": 5000 } ] } ] } } Result: Claude will be blocked from taking PNG screenshots and forced to use type='jpeg', which works correctly with the Anthropic API. Tested and verified - no more media type mismatch errors.

just wanted to say thank you for this

This should be fixed in version 2.0.46. So sorry for the friction, and thank you for reporting!

Doesn't seem to be fixed, still occurring in 2.0.47

Not fixed.

Can confirm, still seeing this on 2.0.47.

Downgrading my VS Code extension to 2.0.36 doesn't work per guidance, I then get:

 API Error: 400 {"type":"error","error":{"type":"invalid_request_error","message":"`clear_thinking_20251015` strategy requires `thinking` to be 
    enabled"},"request_id":"req_011CV9w7LXQaGqmgogERWisW"}

Just resolved to telling Claude to tell me when to take screenshots and then I paste them into VS Code for it. Annoying but I am hoping this gets patched soon.

another user suggested downgrading the cli to 2.0.30 https://github.com/anthropics/claude-code/issues/11975#issuecomment-3555784241

i tried that and im not getting that error anymore.

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