M004 : The Mesh sss uses nnn Bones while SL limit is nnn Bones per Mesh

Your Mesh exceeds the number of allowed weight maps. In Second Life the number of weight maps for a single mesh is limited to 110. If you run into this problem you have 2 options to fix the issue:

  1. You can check if you really need as many weight maps. Often it happens that a weight map is defined but empty (no vertices are assigned to the map). In that case cleaning up your weight maps can get your weight map count below the limit.
  2. You also can cut your mesh into 2 or more objects where each part uses weight maps only up to the allowed limit. Make sure you clean up the weight maps after cutting the parts as mentioned above

Note: Avastar has a tool for cleaning up the weight maps of a mesh:

Cleanup Weight Maps