UBUNTU-gpkg repo eror

 The error you’re encountering indicates that the APT package manager is unable to verify the GPG signature of the MySQL repository because it lacks the necessary public key. This usually happens when a repository is added but its corresponding GPG key is not imported. To resolve this, you need to add the missing public key. The key ID B7B3B788A8D3785C is provided in your error message.

Let’s try another approach from the one in the post you mentioned:

Add the Repository Key:

Open a terminal.

Execute the following command to import the key:

sudo apt-key adv --keyserver keyserver.ubuntu.com --recv-keys B7B3B788A8D3785C

This command tells apt-key to retrieve the key from a keyserver and add it to your system.

Update the Package Lists:

After importing the key, update the package lists:

sudo apt update

This will refresh the list of available packages and incorporate the changes made by adding the new key.

If for some reason, the apt-key adv command does not work (which can happen in certain environments or due to network issues), you can try an alternative method:

Add the Key Using an Alternative Method:

You can download the key and add it manually. Run:

sudo gpg --keyserver keyserver.ubuntu.com --recv B7B3B788A8D3785C
sudo gpg --export --armor B7B3B788A8D3785C | sudo apt-key add -

Then Update the Package Lists again.