Pcbnew crashes and the kicad_pcb file size is nulled if copy/paste items from some board and save
# Steps to reproduce
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1. Place the demo file A1 and A2 in a writable folder.
2. Open file A1 in pcbnew instance 1.
3. Open file A2 in pcbnew instance 2 and call Menu > Edit > Unfill All Zones.
4. Copy all items in pcbnew instance 2 and paste in pcbnew instance 1.
5. Save file in the pcbnew instance 1, then the pcbnew crashes and the file size of A1 is reduced to 0 byte.
> File A1: demos/pic_programmer/pic_programmer.kicad_pcb<br>
> File A2: demos/multichannel/multichannel_mixer.kicad_pcb
PS. Please see comment for simpler steps to reproduce.
# KiCad Version
<!-- Copy version information (from main menu Help->About KiCad ->Copy Version Info) and paste it between the triple backticks below to preserve the formatting. -->
```
Application: KiCad x86_64 on x86_64
Version: 10.0.0-rc1.1-67-g9b67b0238d, release build
Libraries:
wxWidgets 3.2.9
FreeType 2.13.3
HarfBuzz 10.2.0
FontConfig 2.15.0
libcurl/8.14.1 OpenSSL/3.5.3 zlib/1.3.1 brotli/1.1.0 zstd/1.5.7 libidn2/2.3.8 libpsl/0.21.2 libssh2/1.11.1 nghttp2/1.64.0 librtmp/2.3 OpenLDAP/2.6.10
Platform: Ubuntu 25.10, 64 bit, Little endian, wxGTK, Wayland, ubuntu, wayland
Build Info:
Date: Feb 16 2026 00:15:28
wxWidgets: 3.2.9 (wchar_t,wx containers) GTK+ 3.24
Boost: 1.88.0
OCC: 7.8.1
Curl: 8.14.1
ngspice: 44.2
Compiler: GCC 15.2.0 with C++ ABI 1020
Build settings:
KICAD_USE_EGL=ON
KICAD_IPC_API=ON
KICAD_USE_PCH=OFF
Locale:
Lang: en_US
Enc: UTF-8
Num: 1,234.5
Encoded кΩ丈: D0BACEA9E4B888 (sys), D0BACEA9E4B888 (utf8)
```
issue