Work item relation tools (list_work_item_relation_definitions, list_work_item_relations) return 404 via MCP server on self-hosted CE

Support Using Plane
1

Hi,

we’re using the official Plane MCP server against our self-hosted Plane CE workspace. Two of the relation-related tools consistently fail:

  • list_work_item_relation_definitions() (no parameters) → HTTP 404: Not Found: Page not found
  • list_work_item_relations(project_id, work_item_id) → same 404, tested with work items in two different projects in our workspace, so it doesn’t seem to be project- or permission-specific

Other work item tools (list/retrieve work items, creating relations with the built-in dependency types like blocking/blocked_by) work fine against the same workspace.

This matters because create_work_item_relation needs a relation_definition_id for any relation type other than the built-in dependency types (e.g. “relates to”), and without list_work_item_relation_definitions working, we can’t look up that ID at all - so we can’t create “relates to” links between work items in different projects via the API, even though this works fine from the UI.

We found a related (but not identical) issue on the plane-mcp-server GitHub repo, #126, describing self-hosted CE instances not exposing the same REST endpoints the MCP server/SDK expects (e.g. /work-items/ vs. the actual /issues/). Wondering if this is the same root cause for the relations endpoints.

Could someone confirm whether custom work item relations are supported via the REST API on self-hosted CE, and if this is a known/tracked issue?

Setup: self-hosted Plane CE, official Plane MCP server.

2

Hi,

Following up on my previous post about list_work_item_relation_definitions() and list_work_item_relations() failing with 404 via the official Plane MCP server. I’ve now isolated this at the raw REST API level (bypassing the MCP server entirely) to rule out an MCP-side bug:

  • GET /api/v1/workspaces/{slug}/work-item-relation-definitions/ → 404 “Page not found”
  • GET /api/v1/workspaces/{slug}/projects/{project_id}/work-items/{work_item_id}/work-item-relations/ → 404 “Page not found”
  • GET /api/v1/workspaces/{slug}/projects/{project_id}/work-items/{work_item_id}/relations → 200 OK, works fine (returns blocking/blocked_by/relates_to/etc. for built-in dependency types)

So the built-in dependency-type relations endpoint exists and works on self-hosted CE, but both the custom relation definitions endpoint and the per-work-item custom relations endpoint don’t exist on our instance at all — this isn’t an MCP server or SDK bug, the underlying REST routes simply return 404 on self-hosted CE.

This confirms: custom work item relations (anything beyond blocking/blocked_by/relates_to/duplicate/start_after/etc.) can’t be created or queried via the REST API on self-hosted CE, even though the feature is available in the UI. This blocks any automation/API use case that needs custom relation types (e.g. cross-project “relates to” links via a custom definition).

Could someone from the Plane team confirm:

  1. Whether /work-item-relation-definitions/ and /work-item-relations/ are Cloud-only endpoints, or missing due to a self-hosted CE version gap
  2. If there’s a self-hosted release that already includes them
  3. Whether this is tracked internally (happy to raise the issue on another plattform, if that is prefered)

Setup: self-hosted Plane CE, official Plane MCP server / plane-sdk 0.2.19.

3

Thanks for the detailed breakdown. These endpoints are not available on the self-hosted environment yet. They will be going live with Commercial Edition v3.0.0 around mid-July, and will be available on Community Edition at a later date.