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.
Cloning the Unreal Engine repository shows an error.
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__1. Is the Unreal Engine account activated?__ The UE repository is private. In order to clone it, create the [UE](https://www.unrealengine.com/en-US/) account, activate it (check the verification mail), and [link your GitHub](https://www.unrealengine.com/en-US/blog/updated-authentication-process-for-connecting-epic-github-accounts) account.
__2. Is git properly installated?__ Sometimes an error shows incompatibilities with the `https` protocol. It can be solved easily by uninstalling and reinstalling git. Open a terminal and run the following commands.
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.
