Known Issues

Note

Most issues listed here are caused by upstream components (Qt, QtWebEngine, GPU drivers) and cannot be fixed in Zeal directly. Workarounds are provided where possible.

Crash on startup on Windows (outdated Visual C++ runtime)

Zeal crashes on startup with no error message. This is often caused by an outdated or missing Microsoft Visual C++ Redistributable.

Fix: Install or reinstall the latest Visual C++ Redistributable:

winget install --force Microsoft.VCRedist.2015+.x64

Or download it manually from Microsoft.

See: #1658

Crash on startup on Linux (malloc(): invalid size)

Zeal crashes immediately on launch with malloc(): invalid size (unsorted) or similar heap corruption errors. This is caused by GPU driver initialization (NVIDIA or Mesa/Intel) inside QtWebEngine/Chromium corrupting the heap before Zeal runs.

Workaround: Run Zeal with software rendering:

• QT_OPENGL=software zeal
• QTWEBENGINE_CHROMIUM_FLAGS="--disable-gpu" zeal

See: #1769

Display scaling issues on Linux (HiDPI, fractional scaling, Wayland)

Zeal may appear too small, too large, or have blurry/garbled fonts on Linux with HiDPI displays or fractional scaling. These are Qt issues related to how the platform plugin handles display scaling.

Workarounds:

• Blurry or garbled fonts with fractional scaling:

  QT_SCALE_FACTOR_ROUNDING_POLICY="RoundPreferFloor" zeal

• UI too small on HiDPI:

  QT_SCALE_FACTOR=2 zeal

To make these permanent, add the variable to the Exec line in your .desktop file or set it in your environment.

For a full list of Qt scaling options, see Qt High DPI Environment Variables.

See: #1656, #1578

HTTPS downloads fail behind an authenticated proxy

Docset index loads fine, but downloading docsets fails with "server replied: Forbidden". This is a known Qt bug when using HTTPS through a proxy that requires authentication.

Status: No workaround. Upstream Qt bug QTBUG-55960.

See: #666