Problems with Qt?

LudwigJ · Yesterday 15:20:29

I haven't found anyone complaining about this, but after a system update today, several applications are crashing, apparently due to problems with qt.

- Telegram fails thus:

QPainter::begin: Paint device returned engine == 0, type: 2
QWidget::render: Cannot render with an inactive painter
Segmentation fault (core dumped) Telegram

- ebook-viewer fails thus:

[3:3:0100/000000.908457:ERROR:../../../qtwebengine/src/3rdparty/chromium/content/zygote/zygote_linux.cc:621] Zygote could not fork: process_type renderer numfds 5 child_pid -1
[3:3:0100/000000.908513:ERROR:../../../qtwebengine/src/3rdparty/chromium/content/zygote/zygote_linux.cc:653] write: Broken pipe (32)
Segmentation fault (core dumped) ebook-viewer

- qbittorrent is more verbose:

qBittorrent version: v5.2.1

Caught signal: SIGSEGV
```
0# getStacktrace[abi:cxx11]() in qbittorrent
1# 0x00000000001F1364 in qbittorrent
2# 0x000000000003E8F0 in /usr/lib/libc.so.6
3# 0x000000000000E9AC in /usr/lib/libfontconfig.so.1
4# FcCharSetHasChar in /usr/lib/libfontconfig.so.1
5# QFontEngineMulti::stringToCMap(QChar const*, int, QGlyphLayout*, int*, QFlags<QFontEngine::ShaperFlag>) const in /usr/lib/libQt6Gui.so.6
6# QTextEngine::shapeText(int) const in /usr/lib/libQt6Gui.so.6
7# QTextLine::layout_helper(int) in /usr/lib/libQt6Gui.so.6
8# 0x0000000000361B71 in /usr/lib/libQt6Gui.so.6
9# QFontMetrics::size(int, QString const&, int, int*) const in /usr/lib/libQt6Gui.so.6
10# QCommonStyle::sizeFromContents(QStyle::ContentsType, QStyleOption const*, QSize const&, QWidget const*) const in /usr/lib/libQt6Widgets.so.6
11# QFusionStyle::sizeFromContents(QStyle::ContentsType, QStyleOption const*, QSize const&, QWidget const*) const in /usr/lib/libQt6Widgets.so.6
12# QHeaderView::sectionSizeFromContents(int) const in /usr/lib/libQt6Widgets.so.6
13# QHeaderView::sizeHint() const in /usr/lib/libQt6Widgets.so.6
14# QTreeView::updateGeometries() in /usr/lib/libQt6Widgets.so.6
15# QTreeView::doItemsLayout() in /usr/lib/libQt6Widgets.so.6
16# PeerListWidget::PeerListWidget(PropertiesWidget*) in qbittorrent
17# PropertiesWidget::PropertiesWidget(QWidget*) in qbittorrent
18# MainWindow::MainWindow(IGUIApplication*, WindowStateNS::WindowState, QString const&) in qbittorrent
19# 0x00000000001CA1BF in qbittorrent
20# 0x00000000001F081B in /usr/lib/libQt6Core.so.6
21# 0x00000000001F081B in /usr/lib/libQt6Core.so.6
22# QObject::~QObject() in /usr/lib/libQt6Core.so.6
23# 0x000000000029917A in qbittorrent
24# QObject::event(QEvent*) in /usr/lib/libQt6Core.so.6
25# QApplicationPrivate::notify_helper(QObject*, QEvent*) in /usr/lib/libQt6Widgets.so.6
26# QCoreApplication::notifyInternal2(QObject*, QEvent*) in /usr/lib/libQt6Core.so.6
27# QCoreApplicationPrivate::sendPostedEvents(QObject*, int, QThreadData*) in /usr/lib/libQt6Core.so.6
28# 0x000000000049FC98 in /usr/lib/libQt6Core.so.6
29# 0x0000000000061BFD in /usr/lib/libglib-2.0.so.0
30# 0x0000000000063E57 in /usr/lib/libglib-2.0.so.0
31# g_main_context_iteration in /usr/lib/libglib-2.0.so.0
32# QEventDispatcherGlib::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) in /usr/lib/libQt6Core.so.6
33# QEventLoop::exec(QFlags<QEventLoop::ProcessEventsFlag>) in /usr/lib/libQt6Core.so.6
34# QCoreApplication::exec() in /usr/lib/libQt6Core.so.6
35# Application::exec() in qbittorrent
36# main in qbittorrent
37# 0x0000000000027741 in /usr/lib/libc.so.6
38# __libc_start_main in /usr/lib/libc.so.6
39# _start in qbittorrent
```

Segmentation fault (core dumped) qbittorrent

- Other apps like audacious, calibre, etc. fail with a terse Segmentation fault (core dumped)

floriv · Yesterday 15:33:40

I had the same problem. Have you tried restarting yet? After I restarted, I had the same problem as described here:

https://bbs.archlinux.org/viewtopic.php?id=313796

floriv · Yesterday 16:13:58

You can try downgrading fontconfig; that worked for me.

sudo pacman -U https://archive.archlinux.org/packages/f/fontconfig/fontconfig-2:2.17.1-1-x86_64.pkg.tar.zst

LudwigJ · Yesterday 18:05:37

Indeed, downgrading fontconfig to 2:2.17.1-1 solved the problem.
This shouldn't happen, though, should it? Should we report it somewhere?

V1del · Yesterday 18:32:03

Worksforme™ do you potentially have some other tools that might not have been rebuilt yet or similar/are you using a non-standard Qt build/theme? There was a bug in 2.18 fontconfig that "should" be fixed in 2.18.1 is that the version you were running? Some "exotic" fonts?

LudwigJ · Yesterday 18:42:11

Non-standard Qt build/theme? No.
"Exotic" fonts? I can't imagine any of the fonts I use could be classified as "exotic", but then again I'm not sure what kind of founts would be considered "exotic".
For now it Worksforme™, which is all I care for in the short term, since I need urgent access to some documents that happen to be in epub format.
I had fontconfig 2:2.18.1-1, downgrading to 2:2.17.1-1 did the trick. Right now I can't afford to spend time investigating further, maybe tomorrow.

Last edited by LudwigJ (Yesterday 18:43:31)

floriv · Yesterday 18:47:44

V1del wrote:

There was a bug in 2.18 fontconfig that "should" be fixed in 2.18.1 is that the version you were running?

I tested both 2.18 versions, and the problem occurred in both. (The problem occurred this morning)

$ cat /var/log/pacman.log | grep -a fontconfig | grep -Ei 'downgrade|install|upgrade'
[2026-02-18T12:22:15+0100] [ALPM] upgraded fontconfig (2:2.17.1-1 -> 2:2.17.1-1.1)
[2026-06-03T07:48:45+0200] [ALPM] upgraded fontconfig (2:2.17.1-1.1 -> 2:2.18.1-1.1)
[2026-06-03T15:54:30+0200] [ALPM] downgraded fontconfig (2:2.18.1-1.1 -> 2:2.18.0-3)
[2026-06-03T16:04:55+0200] [ALPM] upgraded fontconfig (2:2.18.0-3 -> 2:2.18.1-1.1)
[2026-06-03T18:09:13+0200] [ALPM] downgraded fontconfig (2:2.18.1-1.1 -> 2:2.17.1-1)

V1del wrote:

Some "exotic" fonts?

Do you mean in use or in the Fonts directory? In use: No, I don't think so.

Last edited by floriv (Yesterday 18:52:58)

seth · Yesterday 19:43:33

x-ref, https://bbs.archlinux.org/viewtopic.php?id=313799

archdub · Yesterday 21:47:34

After today's update, Telegram was failing for me with this message:

Telegram
error: empty dic file
Hash Manager Error : 2
QPainter::begin: Paint device returned engine == 0, type: 2
QWidget::render: Cannot render with an inactive painter
qt.gui.imageio.jpeg: Corrupt JPEG data: premature end of data segment

Downgrading (and pinning) fontconfig fixed it for me. Thanks a lot for mentioning that solution.

Update: in Arch gitlab on the issues register for fontconfig, someone suggested that running "fc-cache" would fix the issue. It did not for me. Downgrading fixed it.

Last edited by archdub (Yesterday 22:09:47)

seth · Yesterday 22:05:06

Do you mean in use or in the Fonts directory? In use: No, I don't think so.

Do you have the output of

fc-match -s sans-serif

for either fc version?
It seems the resolution strategy for the generic fonts has changed and something in the resolution chain tries to trigger a crash when testing the glyph coverage.

jb2170 · Today 04:44:11

Downgrading fontconfig worked for me. Cheers!

floriv · Today 09:03:22

seth wrote:

Do you have the output of
fc-match -s sans-serif
for either fc version?

fontconfig 2.17.1
fontconfig 2.18.1

Here's just the diff:

-fontconfig 2:2.17.1-1
+fontconfig 2:2.18.1-1.1
+AdwaitaSans-Italic.ttf: "Adwaita Sans" "Italic"
-DejaVuMathTeXGyre.ttf: "DejaVu Math TeX Gyre" "Regular"
-Hack-Regular.ttf: "Hack" "Regular"
-JetBrainsMono-Regular.ttf: "JetBrains Mono" "Regular"
-LibertinusMath-Regular.otf: "Libertinus Math" "Regular"
-LibertinusMono-Regular.otf: "Libertinus Mono" "Regular"
+LibertinusSans-Regular.otf: "Libertinus Sans" "Regular"
-MathJax_Typewriter-Regular.woff: "MathJax_Typewriter" "Regular"
-NotoKufiArabic-Regular.ttf: "Noto Kufi Arabic" "Regular"
-NotoNastaliqUrdu-Regular.ttf: "Noto Nastaliq Urdu" "Regular"
+NotoSansArabic-Regular.ttf: "Noto Sans Arabic" "Regular"
+NotoSansArmenian-Regular.ttf: "Noto Sans Armenian" "Regular"
-NotoSansMono-Regular.ttf: "Noto Sans Mono" "Regular"
+NotoSansNushu-Regular.ttf: "Noto Sans Nushu" "Regular"
+NotoSansSyriacWestern-Regular.ttf: "Noto Sans Syriac Western" "Regular"
+NotoSansVithkuqi-Regular.ttf: "Noto Sans Vithkuqi" "Regular"
-NotoSerifBalinese-Regular.ttf: "Noto Serif Balinese" "Regular"
-NotoSerifVithkuqi-Regular.ttf: "Noto Serif Vithkuqi" "Regular"
-NotoTraditionalNushu-Regular.ttf: "Noto Traditional Nushu" "Regular"
-Poppins-Regular.ttf: "Poppins" "Regular"
-TheMix-4-SemiLightExp.otf: "TheMix" "SemiLight Expert"
+SourceSansPro-Regular.otf: "Source Sans Pro" "Regular"
+STIXMathJax_SansSerif-BoldItalic.woff: "STIX MathJax SansSerif" "Bold Italic"
+STIXMathJax_SansSerif-Italic.woff: "STIX MathJax SansSerif" "Italic"
+STIXMathJax_SansSerif-Regular.woff: "STIX MathJax SansSerif" "Regular"
+TheSans-2-XLightIta.otf: "TheSans" "ExtraLight Italic"
+TheSans-4-SemiLight.otf: "TheSans" "SemiLight"
+TradeGothic_Bold.ttf: "TradeGothic" "Bold"

seth · Today 14:49:14

The "| sort" is counterproductive in this case - we want to know what gets resolved in which order

floriv · Today 15:16:03

Oops, my bad. Let's try again:

fontconfig 2.17.1
fontconfig 2.18.1

Last edited by floriv (Today 15:21:52)

seth · Today 15:24:30

The head actually remains

NotoSans-Regular.ttf: "Noto Sans" "Regular"
DejaVuSans.ttf: "DejaVu Sans" "Book"
DejaVuSans-Bold.ttf: "DejaVu Sans" "Bold"
DejaVuSans-Oblique.ttf: "DejaVu Sans" "Oblique"
DejaVuSans-BoldOblique.ttf: "DejaVu Sans" "Bold Oblique"
NimbusSans-Regular.otf: "Nimbus Sans" "Regular"

but 2.18 then skips

FontAwesome5Brands-Regular-400.otf: "Font Awesome 5 Brands" "Regular"
FontAwesome5Free-Regular-400.otf: "Font Awesome 5 Free" "Regular"
AdwaitaMono-Regular.ttf: "Adwaita Mono" "Regular"
LibertinusMath-Regular.otf: "Libertinus Math" "Regular"
LibertinusMono-Regular.otf: "Libertinus Mono" "Regular"
LibertinusSerif-Regular.otf: "Libertinus Serif" "Regular"
LinLibertine_R.otf: "Linux Libertine O" "Regular"
LinLibertine_DR.otf: "Linux Libertine Display O" "Regular"
LinLibertine_M.otf: "Linux Libertine Mono O" "Mono"
FontAwesome.otf: "FontAwesome" "Regular"
Poppins-Regular.ttf: "Poppins" "Regular"
NotoNastaliqUrdu-Regular.ttf: "Noto Nastaliq Urdu" "Regular"

and continues w/

LibertinusSans-Regular.otf: "Libertinus Sans" "Regular"
NotoSansBengali-Regular.ttf: "Noto Sans Bengali" "Regular"

instead and there's notably

STIXMathJax_SansSerif-Regular.woff: "STIX MathJax SansSerif" "Regular"
STIXMathJax_SansSerif-Italic.woff: "STIX MathJax SansSerif" "Italic"
STIXMathJax_SansSerif-BoldItalic.woff: "STIX MathJax SansSerif" "Bold Italic"

before reaching Adwaita and Awesome again.

fc-list | grep -i woff

What if you move those away?

floriv · Today 15:45:44

seth wrote:

fc-list | grep -i woff
What if you move those away?

That solves the problem, and there are no errors.

I've noticed that the WOFF files from the MathJax package don't cause any issues (I can include them and start without any error messages).
However, the WOFF files from the “Computer Modern” font family do. It doesn't work with those.

floriv · Today 15:48:54

I manually added the Computer-Modern files in 2012, so it’s possible that a newer version might work. Should I try that to troubleshoot the issue?

Arch Linux

#1 Yesterday 15:20:29

Problems with Qt?

#2 Yesterday 15:33:40

Re: Problems with Qt?

#3 Yesterday 16:13:58

Re: Problems with Qt?

#4 Yesterday 18:05:37

Re: Problems with Qt?

#5 Yesterday 18:32:03

Re: Problems with Qt?

#6 Yesterday 18:42:11

Re: Problems with Qt?

#7 Yesterday 18:47:44

Re: Problems with Qt?

#8 Yesterday 19:43:33

Re: Problems with Qt?

#9 Yesterday 21:47:34

Re: Problems with Qt?

#10 Yesterday 22:05:06

Re: Problems with Qt?

#11 Today 04:44:11

Re: Problems with Qt?

#12 Today 09:03:22

Re: Problems with Qt?

#13 Today 14:49:14

Re: Problems with Qt?

#14 Today 15:16:03

Re: Problems with Qt?

#15 Today 15:24:30

Re: Problems with Qt?

#16 Today 15:45:44

Re: Problems with Qt?

#17 Today 15:48:54

Re: Problems with Qt?

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