We have set the whole website back to version 1.6. with the new update the whole shop was not working anymore and customers could not buy any products. However, it would be best to update everything. Nevertheless, we are a bit scared that we will have the same problem than and our shop will be offline again.
Sorry, but we can’t know what the problem is as we didn’t see the site.
Do you have all plugins up to date?
Perhaps some 3rd-party plugins create conflicts. You may disable them.
Try to upload your site to some test domain and update the theme there to check the issues.
You can leave your current site as it is, just copy all files and database to other test domain to be able to check the issues after update.
You need create a new database for a new domain and import dump of your current database.
You can ask your host how to import/export dump or ask them to do this for you.