[Blender] Material slots cannot be deleted in edit mode. Solution

error

I was wondering if there is a way to efficiently reduce the number of material slots…
Search for “Blender material deletion command/bulk/add-on” on Google.

I found various ways to delete materials

Solution 1. Delete material slots one by one
Solution 2. Understand and remove objects that are assigning unnecessary material slots
Solution 3. Add-on “MatSlotCleaner” that deletes unused materials in bulk
Solution 4. Run command to remove unnecessary materials

This time, I will show you how to deal with the problem that material slots cannot be deleted in edit mode in Blender.

Error “Material slot cannot be deleted in edit mode”

Material slots cannot be deleted in edit mode	Unable to remove material slot in edit mode	无法在编辑模式下移除材质槽
Japanese	English	中国語

Ooccurrence:
1. [Edit mode], [3Dビューのシェーディング ソリッドモード]. Select object.
2. [Material Properties] This happens when you select a material and try to delete it with the [-] button.

I often click the [-] button to delete a vertex group, but for some reason I can’t delete material slots by using the [-] button to reduce the number of materials.

Solution 1: Delete material slots one by one

1. [Object mode], [3Dビューのシェーディング ソリッドモード].Select the object.
2. [Material properties] → Select the material slot you want to delete, and click the [-] button at the top right.

3. The deletion is now complete.

Solution 2: Understand and delete objects that assign unnecessary material slots

1. [Object mode], [3Dビューのシェーディング ソリッドモード] → Select the object. Find the material slot name you want to delete.
2. [Outliner] → [Search box 🔍], Enter the name of the material slot you want to delete and search.
3. As many materials as there are links will appear.

4. Solution 1: Perform strong to delete material slots one by one.

Reference: Blender2.8 How to delete unnecessary materials – soramame style

Solution 3: Add-on “MatSlotCleaner” to delete unused materials in bulk

1. Download MatSlotCleaner.
   I found it by searching Google for “Material Delete Add-on”.

[NazzarenoGiannelli / matslotcleaner][Code] → [Download ZIP]

https://github.com/NazzarenoGiannelli/matslotcleaner

1. Blender Edit → Preferences → Add-ons → Select [Install] matslotcleaner-master.zip and Install Add-ons → Enable.
2. [Object mode], select the [3Dビューのシェーディング ソリッドモード] object.
3. Click [Object Mode], [Object] → [MatSlotCleaner].

4. This allows you to delete unused material slots assigned to objects.

Solution 4: Execute the command to delete unnecessary materials

Article written by Mr. Oberino [Python] Highly practical material-related sample code [Blender] – Bulk replacement of materials, combination of 001 etc., deletion of empty slots, etc. – Please try Oblivion summary.

• Material replacement
• Remove empty slots
• Combine duplicated materials such as .001, .002
• Combine only specific materials

Operating Environment

• Windows 10 Pro 1909
• Blender 2.83, 2.90.1
  • Material Delete Addon NazzarenoGiannelli / MatSlotCleaner – Github
  • Add-on “All Material List” that lists all materials in the project
  • “All Material List” has a function to delete materials all at once