> ## Documentation Index
> Fetch the complete documentation index at: https://mintlify.com/LadybirdBrowser/ladybird/llms.txt
> Use this file to discover all available pages before exploring further.

# Build troubleshooting

> Solutions to common build and runtime issues with Ladybird browser

In case of an error, you might find an answer of how to deal with it here.

***

## Building Ladybird

### CMake fails to configure the build because it's outdated

Ensure your CMake version is >= 3.30 with `cmake --version`. If your system doesn't provide a suitable version of CMake, you can download a binary release from the [CMake website](https://cmake.org/download).

<Info>
  CMake 3.30 or newer is required to build Ladybird.
</Info>

***

### GCC is missing or is outdated

Ensure your gcc version is supported by the build system with `gcc --version`. Otherwise, install it.

If your gcc binary is not called `gcc` you have to specify the names of your C and C++ compiler when you run cmake:

```bash theme={null}
cmake ../.. -GNinja -DCMAKE_C_COMPILER=gcc-13 -DCMAKE_CXX_COMPILER=g++-13
```

<Tip>
  See the [build instructions](/building/build-instructions#build-prerequisites) for supported compiler versions.
</Tip>

***

### Legacy renegotiation is disabled

Ensure your `/etc/ssl/openssl.cnf` file has the following options:

```ini theme={null}
[openssl_init]
ssl_conf = ssl_sect

[ssl_sect]
system_default = system_default_sect

[system_default_sect]
MinProtocol = TLSv1.2
CipherString = DEFAULT@SECLEVEL=1
Options = UnsafeLegacyRenegotiation
```

***

### "Targets may link only to libraries" message (Qt UI on macOS)

When building with the Qt UI on macOS, you may encounter the following message:

```
CMake Warning at /opt/homebrew/Cellar/qt/6.7.0_1/lib/cmake/Qt6/FindWrapOpenGL.cmake:48 (target_link_libraries):
Target "ladybird" requests linking to directory "/usr/X11R6/lib". Targets
may link only to libraries. CMake is dropping the item.
```

…followed by 14-line stack trace, the top of which is this:

```
Build/vcpkg/scripts/buildsystems/vcpkg.cmake:859 (_find_package)
```

<Info>
  Despite the warning message shown in bright yellow, you'll be able to build successfully with the Qt UI. This warning can be safely ignored.
</Info>

***

## Running Ladybird

### Race condition on exit when running headless on systems with llvmpipe

When running `--headless=text` or `--headless=layout-tree` on a UNIX system with the [llvmpipe](https://docs.mesa3d.org/drivers/llvmpipe.html) software rasterizer (common default on virtual machines), Ladybird will occasionally terminate with:

```
double free or corruption (!prev)
```

**Solution:** Run Ladybird with `--force-cpu-painting` to make that go away.

```bash theme={null}
./Build/release/bin/Ladybird --force-cpu-painting --headless=text
```

<Note>
  **Likely explanation:** atexit handlers are registered twice possibly due to llvmpipe and fork/exec interaction issues when starting WebContent process.
</Note>