App Launcher is a Salesforce Identity feature that provides an easy to use SSO (Single Sign-On) portal to launch SSO applications. So, please check whether it was enabled for the profile correctly.

Exception:

“no CustomApplication named standard__AppLauncher found” Exception in Salesforce

Resolution:

Check whether ‘Use Identify Features‘ permission is enabled to the Profile.

If ‘Use Identify Features’ permission is missing for the Profile, please check the following.

1. Navigate to “User Management Settings” under setup. Enable “Enhanced Profile User Interface”.

2. Open the profile. Select “System Permissions”.

Reference Article:

https://help.salesforce.com/s/articleView?id=000331051&type=1