Inconsistent behavior (error message or choices) when opening config gui while destination is unavailable

[Jean-Peer Lorenz]

What I see here, is maybe a feature request. The error message (or choices) that are shown when opening the configuration while the destination is unavailable could be improved. A problem might arise when starting the configuration gui just for running a backup and not for modifying settings.

When running a backup (scheduled or manual), it is checked for the presence of your custom backup destination and used. If the external disk (or whatever is specified) is not found, a message box appears which states: "Destination not found. Please make sure the path exists (e.g. by mounting external disk). You can retry or cancel...". You can now plug in your external disk and proceed or the backup is canceled after 300 sec if you do nothing. I think this is what you expect, isn't it?

Slightly different when opening the configuration. If you open the configuration again, without the external drive being present, another error message is showed: "Destination path not found. It is set to the default value. Check the value before you save your configuration." That is, the destination value is not saved to disk/modified on disk unless you save your configuration again. Closing the configuration without saving will result in no modification of your previous configuration/specified destination. Purpose of this behavior is not to support a non-existing destination path when modifying the configuration. The user is forced to set the destination to an existing path when he/she sets up a backup.