Kicad 9 crashes when opening Kicad 8 schematic

Schematic
1

We have been using the attached project schematic successfully with Kicad 8 but it crashes when opened in Kicad 9. The symptoms are similar to those in KiCad 9.0 Lag When Editing Legacy Schematics. The opening progress bar appears for quite a few seconds (showing a bar of just over 50%) after which it and the Kicad window disappear, requiring Kicad to be reoppened.
When we subsequently try openning the project in Kicad 8, we get a message saying that the the project is already open.
Why does the project crash in Kicad 9.0.1?
We think it’s something to do with file TB1.kicad_sch

Attached are the project zip file and the library file that contains all of the symbols that we use.

Workshop-2025-04-25_162942.zip (306.6 KB)
Signalling_Library.kicad_sym (276.4 KB)
Below is the Version Info for Kicad 8 and Kicad 9.

Kicad 8 version Info:
Application: KiCad x64 on x64

Version: 8.0.8, release build

Libraries:
wxWidgets 3.2.6
FreeType 2.13.3
HarfBuzz 10.0.1
FontConfig 2.15.0
libcurl/8.10.1-DEV Schannel zlib/1.3.1

Platform: Windows 10 (build 19045), 64-bit edition, 64 bit, Little endian, wxMSW
OpenGL: Intel, Intel(R) UHD Graphics, 4.6.0 - Build 27.20.100.8190

Build Info:
Date: Jan 11 2025 18:59:49
wxWidgets: 3.2.6 (wchar_t,wx containers)
Boost: 1.86.0
OCC: 7.8.1
Curl: 8.10.1-DEV
ngspice: 44
Compiler: Visual C++ 1942 without C++ ABI

Build settings:

Kicad 9 version Info:
Application: KiCad x64 on x64

Version: 9.0.1, release build

Libraries:
wxWidgets 3.2.6
FreeType 2.13.3
HarfBuzz 10.2.0
FontConfig 2.15.0
libcurl/8.11.1-DEV Schannel zlib/1.3.1

Platform: Windows 10 (build 19045), 64-bit edition, 64 bit, Little endian, wxMSW

Build Info:
Date: Mar 30 2025 01:11:30
wxWidgets: 3.2.6 (wchar_t,wx containers)
Boost: 1.86.0
OCC: 7.8.1
Curl: 8.11.1-DEV
ngspice: 44
Compiler: Visual C++ 1942 without C++ ABI
KICAD_IPC_API=ON

Locale:
Lang: en_GB
Enc: UTF-8
Num: 1,234.5
Encoded кΩ丈: D0BACEA9E4B888 (sys), D0BACEA9E4B888 (utf8)

2

Why does the project crash in Kicad 9.0.1?

Because the programmers have placed a bug in the program. It should be presented to users during the easter weekend, but it seems the timing is 4…5 days off.

I have opened a gitlab issue with your project. If you experience such a behaviour (crash) the next time you could open the bug report yourself (kicad–>Help–>report bug. Needs gitlab account). A crash is always a bug and not a user error.

When we subsequently try openning the project in Kicad 8, we get a message saying that the the project is already open.

This is because kicad creates lock-files to prevent file modification from different kicad instances. If kicad crashes the lock files remain, so kicad thinks (at the next start, with v8) that the files are still open. Either ignore the warning (in this case you know that the files are not open anymore) or delete the *.lck files in the project directory.