I am new to blender and 3d modeling. I have a rigged model which has a few working animations. I'm trying to create an object for an item of clothing or accessory by duplicating a segment of the mesh pressing P and separating by selection. In pose mode I get the expected behavior since the new objects inherit the weight painting after duplication.

However, When I return to the animation tab the animation is broken. In the dope sheet, bones are underlined in red as if the are missing a dependency or were renamed. I would like to know if this is a bug and how to work around it or if I can change workflow to avoid messing up the animations in the future.

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Here is a video starting with the clean file and working animation and the steps taken resulting in a broken state for the animation. https://youtu.be/UoxxfoX_yOk

  • 1
    $\begingroup$ Missing animation bones links have absolutely nothing to do with modifying the mesh, they are completely unrelated, as the animation works on bones and bones move the mesh. Theese missing links are between animation and bones, so any change of the mesh can't have any impact. If you didn't change the rig it means that the problem existed before your edits. $\endgroup$ Sep 20, 2021 at 9:12
  • $\begingroup$ I have a save file created before any edits where the animations work fine. I have gone back to this save repeatedly and carefully applied only the changes described but the result is always the same. It feels like a bug to me but I don't have the experience in blender to know or understand a workaround. If it helps, I can list the exact sequence of keys which consistently cause the animations to enter a bad state. $\endgroup$
    – mstockfo
    Sep 20, 2021 at 12:55
  • $\begingroup$ One thing that would help would be to add your before and after blend files to your question. (How to add a blend file) $\endgroup$ Sep 20, 2021 at 14:07

1 Answer 1


When you change the active action in the Animation tab, you are changing the action for the currently selected object. At the beginning of the video, the object you have selected is the armature - this is correct. At the end of the video, the object you have selected is the headband mesh - this is incorrect.

The red squigglies are shown on curves that target things that don't exist. In this case, they target pose bones, but you have a mesh selected and meshes don't have pose bones, only armatures do.

So you should be changing the action on the armature object instead. Just select the armature before you change actions (around the 3:00 minute mark in your video).

  • $\begingroup$ Thanks a ton, this was the issue. I thought I had ruled this out but it takes just a second for the red underlined links to change after switching back to the armature. $\endgroup$
    – mstockfo
    Sep 20, 2021 at 14:18

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