Name of the deployment preview error
Installed packages cannot be added/deleted through Salto
Sample error message
Package with namespace SBQQ cannot be installed using Salto. Please install the package directly from Salesforce's AppExchange and fetch.
Package with namespace SBQQ cannot be uninstalled using Salto. Please uninstall this package directly from Salesforce's AppExchange and fetch.
When will I see this deployment preview error?
This error occurs when you select an installed package (i.e., managed package, etc. ) for deletion or addition via a Salto deployment.
This would only be possible when the installed package does not exist in the target org. For example, the source org may have CPQ installed, but the target org does not.
How does this affect my deployment?
The selected installed package will be skipped and will not be deployed.
How can I fix this error?
Avoid selecting installed packages in Salto deployments and make any changes necessary (installation, upgrade and deletion) via the Salesforce UI or the Appexchange.
You can learn more about deployment preview errors here.