How do I fix ‘Reticulating Splines’ or ‘Action taking a long time’ when installing AtlasOS?

When running the Playbook, some users might experience these messages:

Most of the time, this isn’t an issue and is likely due to a slow internet connection or computer. However, it could be stuck if it has been on this screen for a long time. In that case, scroll down to see solutions.

AME Wizard 'Apply Playbook' window demonstrating what 'Reticulating Splines' and 'Action taking a long time' looks like


  1. Ensure that you’re on a fresh install of fully updated Windows. It is highly recommended to following the official AtlasOS installation guide for this. Installing Atlas on a non-fresh Windows installation is considered unsupported and can cause the Playbook to get stuck.

  2. Make sure that your hardware is stable. If you have overclocks, try turning them off.

  3. Remember that only the latest version of the Atlas Playbook is supported.


Restarting and re-applying the Playbook

You can restart Windows and attempt to re-apply the Playbook on a fresh startup. Again, ensure that Windows is updated, and try re-running the Playbook.

Killing the responsible process

Click Show logs at the ‘Action is taking a long time’ status, open Output.txt, and scroll to the bottom to see what is stuck. If it’s a PowerShell or Command Prompt action, you can kill those in the ‘Details’ section of Task Manager. Alternatively, if it’s DISM, you would kill DISM instead.

However, please remember that these actions are responsible for specific functionality in Atlas, so interrupting them could cause an incomplete installation. Re-applying the Playbook is preferred if it works.

Reporting the issue or asking for help

Consider asking for help on the Discord server or forums. Make sure to include your Output.txt log.