VPN + Opening Project = Crash

Development Getting Started & Setup
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1

Hi there…

I currently encounter a strange problem.

My Projects won’t open, as long as my Cyberghost VPN is connected.

Always fatal crashes with:

Unable to use default cache graph 'InstalledDerivedDataBackendGraph' because there are no writable nodes available.

Directly on Startup.

It works well when VPN is offline, but I really would love to have my VPN active…

Is there a way to get this running?

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2

Is there any solution?

or is it really only to toggle the VPN off and on everytime i need to recompile/restart the project?

3

Same isuue, did you fixed it?

4

Same here, but with X-vpn, also crushes even if i just turn on vpn durind editing the project…Not that i need vpn to acces UE5, but i prefer not to see advertisments based on my ip since i don’t know the language of a country i am living in

5

Greetings @BDC_Patrick

VPN’s are not uncommon culprits for this type of thing. I’d suggest going into your VPN settings and adding exceptions for your UE exe as well as enabling LAN access if it’s a setting. VPN’s are pretty notorious for blocking LAN connections.

6

Hi,
The error you’re encountering indicates that Unreal Engine is unable to access the necessary writable cache due to restrictions likely caused by the CyberGhost VPN. This is a common issue with VPNs that alter network configurations, impacting Unreal Engine’s ability to resolve paths or connect to required services.

Here’s how you can address this issue:

  1. Exclude Unreal Engine from the VPN (Split Tunneling)

Many VPNs, including CyberGhost, support split tunneling, which allows you to exclude specific applications or paths from being routed through the VPN.

  • Open CyberGhost VPN.
  • Go to Settings and locate the Split Tunneling feature (often under Privacy or Advanced).
  • Add the Unreal Engine executable (UE4Editor.exe or similar) and any related processes to the exclusion list.
  • Test opening your project.
  1. Configure CyberGhost to Allow Local Network Access

VPNs often block access to local networks, which can interfere with Unreal Engine. Ensure that local networking is permitted.

  • Open the CyberGhost VPN client.
  • Look for an option like **“Allow local network access” or “Bypass LAN” in the settings and enable it.
  • Restart CyberGhost and Unreal Engine.
  1. Specify a Custom Cache Directory for Unreal Engine

Unreal Engine may have issues with the default cache directory when using a VPN. You can set a custom cache location that is more stable.

  1. Locate your Unreal Engine project’s configuration file, typically:

javascript
code

<ProjectDirectory>/Saved/Config/Windows/Engine.ini
  1. Open it in a text editor and add the following:

ini
code

[InstalledDerivedDataBackendGraph]
Path=<CustomWritablePath>

Replace <CustomWritablePath> with a directory you know is writable (e.g., outside of the VPN scope).
3. Save the file and restart Unreal Engine.

  1. Change the VPN Server/Protocol

The VPN server location and protocol may impact your system’s file operations.

  • In CyberGhost, switch to a different server (preferably closer to your region).
  • Try changing the VPN protocol (e.g., WireGuard, OpenVPN, or IKEv2) under the settings.
  1. Temporarily Disable CyberGhost Features

Some CyberGhost features can interfere with local operations:

  • Block online tracking: disable this if it’s enabled.
  • Content Blocker**: Turn off temporarily.
  • Data compression: ensure it’s disabled.

After disabling, test whether Unreal Engine starts properly.

  1. Use Command-Line Options to Force a Graph

If nothing else works, you can try forcing a specific backend graph for the Derived Data Cache (DDC) via the command line:

  1. Launch Unreal Editor with the following parameter:

code

UE4Editor.exe -ddc=PATH_TO_CUSTOM_CACHE

Replace PATH_TO_CUSTOM_CACHE with a custom, writable cache directory as mentioned earlier.

  1. General Troubleshooting

*Ensure Project Files Are Writeable: Ensure no project files or cache folders are locked due to the VPN.

  • Clear DDC Manually: Delete Derived Data Cache folders:

code

<EngineInstallPath>/DerivedDataCache
<ProjectFolder>/Intermediate/DerivedDataCache

Unreal will recreate them on startup.

Final Option

If no workaround works, you may indeed have to toggle the VPN off during project sessions. However, following these steps should minimize disruptions caused by the VPN.

Let me know how these suggestions work for you!

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