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Iris Installed on Server

A server reports a missing shader pipeline because a shader loader like Iris was installed on it. Shader loaders are client-only, the server has no rendering pipeline for them to use.

What does this error mean?
'Shader pipeline missing (client-only)' means a shader loader expected client rendering infrastructure that does not exist on a dedicated server. Shaders and their loaders run entirely on the client. 
Shader pipeline missing (client-only)
Most Common Causes
  • A shader loader (Iris/OptiFine) placed on the server.
  • Copying client rendering/shader mods to the server.
  • Believing shaders run server-side.
  • A pack that did not exclude shader mods from the server.
  • Mirroring the client mods folder.
How To Diagnose
  1. Confirm the message points to a client-only shader pipeline.
  2. Check the server mods folder for shader loaders.
  3. Recall shaders are purely client-side.
  4. Look for accompanying client rendering mods (Sodium).
Recommended Fixes
  • Remove the shader loader
    Delete Iris/OptiFine (and Sodium) from the server, install them on clients only.
  • Keep shaders client-side
    Shaderpacks and loaders belong on each player's client, never the server.
  • Use server-side optimizers
    For server performance, use Lithium, not client shader/rendering mods.
  • Audit server mods
    Remove any other client-only rendering mods present.
Analyze My Log
Frequently Asked Questions

Dedicated servers do not render graphics, so there is no shader/rendering pipeline at all.

On each player's client, loaded by Iris or OptiFine locally.

Yes, with the shader loader gone, the server has nothing trying to find a client pipeline.