I recently updated to 19.04. When I search for files in the dash, I have the following result:
The white one points to the default app:
And the orange one to:
The problem is the default app sometimes does not load. The other one always loads.
What is the difference between these two? How to fix the issue of the default one not loading?
You have an additional file manager installed in addition to the default file manager, nautilus. The appearance of the screenshot makes me suspect that the second one is nemo. They are different file managers, but they have similarities. That is because nemo actually has been based on nautilus many years ago, and then has continued its own development. These file managers are deeply integrated into the system. It is not a good idea to have them installed together within the same desktop environment.
It is difficult to troubleshoot the "sometimes non starting" issue. Having also nemo installed could be part of the issue, but there might be other issues with your current operating system.
Warning ahead: make sure you have an updated backup of your user data before attempting troubleshooting
1 - I would advise as a first troubleshooting step to remove nemo from this system. You can use software center, but a more complete removal is achieved with following terminal command:
sudo apt purge nemo && sudo apt autoremove
2 - If the issue persists (after a reboot), then check whether it is related to your account settings. Create a new account, and log into that new account. If the issue is gone, you know it is related with issues in your current user account settings. You may then permanently move to the new account, or reset your existing account.
3 - If the issue persists in a fresh account, then you may try whether purging and reinstalling nautilus solves the issue. To that aim, you should boot in a recovery terminal with root permissions and network access, purge nautilus and then reinstall. A good way to do this is by reinstalling the ubuntu-desktop metapackage, as that will check that everything belonging to a standard Ubuntu desktop is in place:
apt purge nautilus
apt autoremove
apt install ubuntu-desktop
4 - If this also fails, you will need to reinstall fresh. This will give you a fresh and clean new operating system, which will not be plagued by the default file manager, nautilus, sometimes not starting.
