The new s-expression schematic and symbol library file formats are now the default and should be available as soon as the nightly builds are complete. All new schematics and symbol libraries will be created using the new file formats. All existing schematics will be converted to the new file format on the first load and all subsequent changes will be made to the new file format. The old schematic files remain unchanged and no further edits will be made made. It is still a good idea to make a backup of all existing schematic files just in case something goes wrong.
There are a few things to be aware of when switching between the 5.1 and development branches:
Please allow all library symbol rescuing and remapping to complete to ensure that the library symbols will be saved to the schematic files. If either of these steps are aborted, saving the schematic will certainly result in broken symbol links which will require manual intervention to resolve.
The symbol library cache is no longer required for the new file format. Converting back to the legacy file format may result in broken symbol links so avoid converting between formats. Schematics are now fully portable without the cache library.
Version control software users must add the new schematic files (*.kicad_sch) to ensure change control is maintained.
In the short term, the ability to save schematics and symbol libraries to the old file format will be maintained for testing purposes. Once new schematic and/or symbol library features are added, saving to the old file format will be deprecated to prevent data loss between format conversions.
The new schematic file format fixes a long standing bug when sharing schematic files between projects. Prior to the new file format, sharing files between projects in a simple hierarchical design required the symbol annotation to be maintained in the shared file(s). This limitation has been removed and the annotation can be changed in the shared file because annotations for the entire project are saved in the root schematic file. Root schematics can also be shared by other projects as well because annotations in hierarchical sheet schematic files are ignored and are not changed by the project.
If you find any issues, please be sure to file a bug report at GitLab so that it can be fixed as quickly as possible.
Thank you for your patience as we work through any issues with the new file formats. Once the existing feature set is stable, expect to see new schematic and symbol library features added fairly quickly.
KiCad Development Team