Here is the issue. When I select the "Mosaico Templates” in the drop down menu in Civi under “Mailings” I get a “Safari can’t open the page” message. Any ideas around how to fix this? I get the same message when I select "New Mailing" in the Civi drop down as well. What is wrong? Trevor
Welcome Flyingbow! I encourage you to edit your question to provide the version of CiviCRM and Mosaico so people can help you better. It would also help to see the URL that generates the "Safari can't open the page" error.
There's a known issue with Mosaico 2.9 that is fixed in CiviCRM 5.47.2. So if you're using Mosaico 2.9, make sure you're on the very latest CiviCRM.
You might also get an error if this is a copy of an existing CiviCRM site (perhaps a test site) and you're using a template generated on another site. If so, the Mosaico README has a note to run this in MySQL:
UPDATE civicrm_mosaico_template SET metadata = replace(metadata, 'old-domain.org', 'new-domain.org');
If this is a "migrated" site and MySQL isn't an option, please comment on my answer and we can use a workaround.