Reference/Release Notes/3.0/Core

Blender 3.0: Core

Blend file read & Write

Forward Incompatibility Breakage
Blend files saved in Blender 3.0 with compression enabled won't load in older versions of Blender.

  • The speed when opening a blend file linking many (thousands or more) data-blocks from a same library has been greatly improved (T89194, D11757, rBdb4fe8e3).
  • Loading .blend files compressed using the Zstandard algorithm is now supported and saving files with compression enabled uses Zstandard instead of gzip (D5799, rB2ea66af7). This improves loading and saving speed while producing files of similar size:
Saving time Uncompressed gzip Zstd Change gzip to Zstd
2.81 splash 0.12s 9.30s 0.46s -95%
2.92 splash 0.12s 11.03s 0.82s -94%
Ember Forest 0.05s 2.57s 0.19s -92%
Mr. Elephant 0.06s 2.19s 0.23s -89%
Loading time Uncompressed gzip Zstd Change gzip to Zstd
2.81 splash 0.23s 1.36s 0.33s -75%
2.92 splash 0.22s 2.23s 0.82s -63%
Ember Forest 0.09s 0.58s 0.19s -66%
Mr. Elephant 0.09s 0.59s 0.19s -66%
File size Uncompressed gzip Zstd Change gzip to Zstd
2.81 splash 386M 334M 334M 0%
2.92 splash 380M 291M 284M -2%
Ember Forest 105M 71M 65M -8%
Mr. Elephant 112M 66M 63M -5%
  • zstandard package was added to bundled python to enable scripts to manipulate zstd-compressed .blend files (rBa5917175).

Collections & View Layers

  • The process re-syncing Layer collections in View layers to match with current Collections hierarchy in the scene has been enhanced to enable re-using as much as possible exiting layers. This often avoids losing layer-specific settings (like the Exclude flag) when re-organizing the collections, and allows for future improvements like adding custom properties to layers (D12016, rBb18d0244, rB3db37075).

Library Overrides

Forward Incompatibility Breakage
This means that loading blend files saved in Blender 3.0 in an older version of Blender will loose data (namely, inserted local modifiers, constraints etc. may be lost or misplaced).

  • Basic RNA API has been extended and should now allow all necessary operations (see T86656 for details).
  • Lots of polishing and fixes was done, in particular in the (auto-)resync process, and to enhance the support of complicated features like point caches.

Proxy Removal

Proxies are being removed from Blender in the 3.x series. For 3.0 this process includes:

* Removal of operators to create proxies from linked data-blocks.
* Automatic conversion of proxies to library overrides on file load.

Proxy evaluation code remains for the time being, and it is still possible to skip automatic conversion of proxies in existing .blend files by disabling the Proxy to Override Auto Conversion user preferences Experimental setting.

See also T91671.


  • Vertex group names are now stored in the meshes directly instead of objects. (rB3b6ee8ce, rBfc32567c)
    • It is impossible to have a different list of names in different objects using the same mesh.
    • When opening an older file only one of the available name lists would be chosen for each mesh (preferring the longest), and others are discarded.
    • When linking a mesh object from 2.93 in 3.0, if the object is made local but the mesh remains linked, Blender will not be able to read the mesh's vertex groups. See T93778 for more details.
    • A method of using different vertex group names to reference different bones on multiple objects that use the same mesh will no longer work. See TT94634 for more details.