Upgrading from 1.2.3

I don’t understand the upgrade procedure from 1.2.3. to 3. Instructions say "Delete or move aside everything from within backlight/ except backlight/custom and backlight/data. Does this mean from the upgrade folder or from the website folder? Then, following the instructions to upload the installer, it wants to overwrite the Backlight folder anyway. What are supposed to do with the aforementioned non-deleted folders, assuming they’re on the website? Please explain. Thanks.

It means to delete everything from your existing site except those folders noted.
When you upload the Backlight 3 files, do not upload the backlight/data or backlight/custom/ folders.
(The data/ and custom/ folders inside of the backlight/ folder)
this might make it clearer:

In case you were using phplugins, there is a short faq topic about necessary changes here in the forum: Updating PHPlugins from Backlight 1

Okay thanks for that, big help. One more problem: Theater add-on is installed in modules folder, but does not show up in “modules” on the dashboard. I have cleared the template cache. I may have ordered it via another email. Currently using [redacted], old address was [redacted].

Thanks for your speedy replies!!

You will need the latest version of Theater. The old one that was compatible with Backlight 1 won’t work. I don’t know if upgrade pricing still applies or not. See this blog post:

I’ve removed the email addresses from your message above, as we don’t want them scraped by bots, etc. for purposes of spamming you.

Of course, didn’t think of that, duh. Thank you. I spent the money on the Theater and now all’s swell.