I am having trouble re-installing Create Launcher. I downloaded it two days ago but my Ubuntu was acting weird. Because I am new to Linux/Ubuntu, I un-installed it and re-installed it. I am trying to get Create Launcher back. I did the troubleshoot method of adding the deb line into the update manager under the other software tab but it comes up with an error.
If someone could give me a step by step way of reinstalling it, I would appreciate it.
The problem that you are experiencing is that the source of software that you have manually added is not trusted by default, unless you specifically import a key from a trusted source (usually keyserver.ubuntu.com). That way, when you import software from an archive outside of ubuntu.com you can be sure that this software has not been spoofed.
Please open a terminal and paste the following line:
sudo apt-key adv --recv-keys --keyserver keyserver.ubuntu.com E131728675254D99
This command will import the key from ubuntu.com and add it to your keyring. After that, either run the software update from GUI, or paste the following into your terminal:
sudo apt-get update
sudo apt-get upgrade
See also How do I fix the GPG error "NO_PUBKEY"?.
