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hermes - 💡(How to fix) Fix [Bug]: `hermes mcp serve` fails to start on NixOS [1 pull requests]

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Error Message

Traceback (most recent call last): File "/nix/store/g8glbz7mksy124p938ky9zrjjkbpl6sg-hermes-agent-env/bin/hermes", line 10, in <module> sys.exit(main()) ^^^^^^ File "/nix/store/g8glbz7mksy124p938ky9zrjjkbpl6sg-hermes-agent-env/lib/python3.12/site-packages/hermes_cli/main.py", line 10963, in main args.func(args) File "/nix/store/g8glbz7mksy124p938ky9zrjjkbpl6sg-hermes-agent-env/lib/python3.12/site-packages/hermes_cli/main.py", line 10124, in cmd_mcp mcp_command(args) File "/nix/store/g8glbz7mksy124p938ky9zrjjkbpl6sg-hermes-agent-env/lib/python3.12/site-packages/hermes_cli/mcp_config.py", line 749, in mcp_command from mcp_serve import run_mcp_server ModuleNotFoundError: No module named 'mcp_serve'

Root Cause

Root Cause Analysis (optional)

Fix Action

Fixed

Code Example

Traceback (most recent call last):
  File "/nix/store/g8glbz7mksy124p938ky9zrjjkbpl6sg-hermes-agent-env/bin/hermes", line 10, in <module>
    sys.exit(main())
             ^^^^^^
  File "/nix/store/g8glbz7mksy124p938ky9zrjjkbpl6sg-hermes-agent-env/lib/python3.12/site-packages/hermes_cli/main.py", line 10963, in main
    args.func(args)
  File "/nix/store/g8glbz7mksy124p938ky9zrjjkbpl6sg-hermes-agent-env/lib/python3.12/site-packages/hermes_cli/main.py", line 10124, in cmd_mcp
    mcp_command(args)
  File "/nix/store/g8glbz7mksy124p938ky9zrjjkbpl6sg-hermes-agent-env/lib/python3.12/site-packages/hermes_cli/mcp_config.py", line 749, in mcp_command
    from mcp_serve import run_mcp_server
ModuleNotFoundError: No module named 'mcp_serve'

---

Report       https://paste.rs/dmgMs
  agent.log    https://dpaste.com/AQFVAC9TC
  gateway.log  https://paste.rs/iIqcB

---
RAW_BUFFERClick to expand / collapse

Bug Description

I have hermes running on NixOS using the provided module. The command hermes mcp serve fails to start.

Steps to Reproduce

  1. Run hermes mcp serve

Expected Behavior

The mcp server start.

Actual Behavior

The following import exception is raised:

Traceback (most recent call last):
  File "/nix/store/g8glbz7mksy124p938ky9zrjjkbpl6sg-hermes-agent-env/bin/hermes", line 10, in <module>
    sys.exit(main())
             ^^^^^^
  File "/nix/store/g8glbz7mksy124p938ky9zrjjkbpl6sg-hermes-agent-env/lib/python3.12/site-packages/hermes_cli/main.py", line 10963, in main
    args.func(args)
  File "/nix/store/g8glbz7mksy124p938ky9zrjjkbpl6sg-hermes-agent-env/lib/python3.12/site-packages/hermes_cli/main.py", line 10124, in cmd_mcp
    mcp_command(args)
  File "/nix/store/g8glbz7mksy124p938ky9zrjjkbpl6sg-hermes-agent-env/lib/python3.12/site-packages/hermes_cli/mcp_config.py", line 749, in mcp_command
    from mcp_serve import run_mcp_server
ModuleNotFoundError: No module named 'mcp_serve'

Affected Component

Other

Messaging Platform (if gateway-related)

No response

Debug Report

Report       https://paste.rs/dmgMs
  agent.log    https://dpaste.com/AQFVAC9TC
  gateway.log  https://paste.rs/iIqcB

Operating System

NixOS unstable

Python Version

3.12.13

Hermes Version

Hermes Agent v0.13.0 (2026.5.7) Project: /nix/store/g8glbz7mksy124p938ky9zrjjkbpl6sg-hermes-agent-env/lib/python3.12/site-packages Python: 3.12.13 OpenAI SDK: 2.24.0

Additional Logs / Traceback (optional)

Root Cause Analysis (optional)

No response

Proposed Fix (optional)

No response

Are you willing to submit a PR for this?

  • I'd like to fix this myself and submit a PR

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hermes - 💡(How to fix) Fix [Bug]: `hermes mcp serve` fails to start on NixOS [1 pull requests]