Some of the most common issues regarding CARLA installation and builds are listed hereunder. Some more can be found in the [GitHub issues][issuelink] for the project. In case any doubt is not listed here, take a look at the forum and feel free to post it.
Unreal Engine on Linux requires much more disk space as it keeps all the intermediate files. [This thread](https://answers.unrealengine.com/questions/430541/linux-engine-size.html) discusses the matter.
CARLA is a very performance demanding software. At the very minimum it needs for a 4GB GPU or, even better, a dedicated GPU capable of running Unreal Engine.
* __Run Unreal Engine 4.24.__ Something may have failed when building Unreal Engine. Try running UE editor on its own and check out that it is the 4.24 release.
* __UE4_ROOT is not defined.__ The environment variable is not set. Remember to make it persistent session-wide by adding it to the `~/.bashrc` or `~/.profile`. Otherwise it will need to be set for every new shell. Run `export UE4_ROOT=~/UnrealEngine_4.24` to set the variable this time.
* __Check dependencies.__ Make sure that everything was installed properly. Maybe one of the commands was skipped, unsuccessful or the dependencies were not suitable for the system.
* __Delete CARLA and clone it again.__ Just in case something went wrong. Delete CARLA and clone or download it again.
* __Meet system requirements.__ Ubuntu version should be 16.04 or later. CARLA needs around 15GB of disk space and a dedicated GPU (or at least one with 4GB) to run.
Other specific reasons for a system to show conflicts with CARLA may occur. Please, post these on the forum so the team can get to know more about them.
There is no `CarlaUE4.exe` executable in the source version of CARLA. Follow the [build instructions](build_windows.md) to build CARLA from source. To directly get the `CarlaUE4.exe`, follow the [quick start instructions](start_quickstart.md).
Different issues may result in this specific error message. The user [@tamakoji](https://github.com/tamakoji) solved a recurrent case where the source code hadn't been cloned properly and the CARLA version could not be set (when downloading this as a .zip from git).
*__Check the `Build/CMakeLists.txt.in`.__ If it shows like `set(CARLA_VERSION )` do the following.
__1.__ Go to `Setup.bat` line 198.
__2.__ Update the line from:
```sh
for /f %%i in ('git describe --tags --dirty --always') do set carla_version=%%i
```
to:
```sh
for /f %%i in ('git describe --tags --dirty --always') do set carla_version="0.9.9"
This issue occurs when trying to use the _make_ command either to build the server or the client. Even if CMake is installed, updated, and added to the environment path. There may be a conflict between Visual Studio versions.
Visual Studio is not good at getting rid of itself. To completely clean Visual Studio from the computer go to `Program Files (x86)\Microsoft Visual Studio\Installer\resources\app\layout` and run `.\InstallCleanup.exe -full`. This may need admin permissions.
To keep other Visual Studio versions, edit ```%appdata%\Unreal Engine\UnrealBuildTool\BuildConfiguration.xml``` by adding the following lines.
* __Download the assets.__ The server will not be able to run without the visual content. This step is mandatory.
* __Visual Studio 2017.__ If there are other versions of Visual Studio installed or recently uninstalled, conflicts may arise. To completely clean Visual Studio from the computer go to `Program Files (x86)\Microsoft Visual Studio\Installer\resources\app\layout` and run `.\InstallCleanup.exe -full`.
* __Delete CARLA and clone it again.__ Just in case something went wrong. Delete CARLA and clone or download it again.
* __Meet system requirements.__ CARLA needs around 30/50GB of disk space and a dedicated GPU (or at least one with 4GB) to run.
Other specific reasons for a system to show conflicts with CARLA may occur. Please, post these on the forum so the team can get to know more about them.
Download the [dependencies](http://gnuwin32.sourceforge.net/downlinks/make-dep-zip.php) and extract the _bin_ content into the __make__ installation path.
Some scripts have requirements. These are listed in files named __Requirements.txt__, in the same path as the script itself. Be sure to check these in order to run the script. The majority of them can be installed with a simple `pip` command.
Sometimes on Windows, scripts cannot run with just `> script_name.py`. Try adding `> python script_name.py`, and make sure to be in the right directory.
NVIDIA drivers may be outdated. Make sure that this is not the case. If the issue is still unresolved, take a look at the [forum](https://forum.carla.org/) and post the specific issue.
One of the libraries needed has not been properly installed. As a work around, go to `carla\Build\zlib-source\build`, and copy the file named `zlib.dll` in the directory of the script.
This happens from time to time due to Linux updates. There is a special target in the Makefile for this issue. It takes a long time but fixes the issue:
Alternatively, it is possible to compile a binary version of CARLA within Unreal Editor. Open the CarlaUE4 project, go to the menu `File/Package Project`, and select a platform. This may take a while.
