Section 2: "Patch Day, Oh Noes!"
(what to do and NOT do on patch days)
Q: Hey, a new patch is out! What should I do to ensure my addons keep working error-free?
A: Well, there's no guarantee that your addons will work error-free after a patch, since it is Blizzard's prerogative to change any and all of the API used by various AddOns. When that happens, AddOns which call upon those API functions tend to either not work, work strangely, or throw up lots of nasty-looking error messages.
The absolute best advice I can give for patch-day addon maintenance is to follow these guidelines (credit to Trimble; edits by Syllani)
0) Remove ANYTHING in Interface/FrameXML and disable any addons which provided files that went in there.
If you use a FrameXML based addon, you almost always REQUIRE an updated version after a patch. Since FrameXML files actually *overwrite* the default Blizzard files, and because frequently several FrameXML files update, the author needs to re-integrate their changes with the updated Blizzard files before the mod will work as expected. Better to just removed them from the equation first-thing.
1) Download the new patch on a patch day.
2) Log in to the game and get to the character selection screen. (If prompted about some of your addons being out-of-date, choose "Disable".)
3) Go into the Addons screen by clicking the Addons button in the lower left corner of the screen.
At this point, you should observe that all addons are auto-disabled due to version mismatch. If not, then the patch didn't change the UI, and you don't have to do anything. If they are disabled, proceed with these steps.
4) UNCHECK the check box for every addon.
5) Turn off version checking. (Enable out-of-date addons)
6) Re-check the check box for any addons that you KNOW will work without changes.
7) Log in and test that everything works.
8) Log Out to the character selection screen and go back into Addons
9) Re-check one addon. Log in and test that everything still works.
10) repeat steps 8 and 9 for each addon you have. I recommend standing in an Inn to do this - it's faster.
If something kills your system, Kill the wow process via task manager (or coldboot your system if you have to)
11) Watch for updates to your favorite mods.
12) When you see an update, download the update and replace the mod with the new version.
13) Repeat step 12 until all of your mods are updated.
There is no harm in leaving version checking turned off permanently.
These steps will ensure a clean and aggrivation free mod using experience. They will ensure that you don't spend hours trying to figure out exactly what killed your system. When 1300 patch initially came out, the StandAlone version of QuestMinion totally locked up everyone's machine, requiring a coldboot. It was a pain to figure out which mod did it.
In short:
Many mods will still work after a patch, even though they are technically "out of date". You only *have* to update mods that are actually
broken because of functionality changes made by Blizzard in a patch. If you aren't getting error messages and everything is still working okay, you can just run using the "Load Outdated AddOns" check box. It is a good idea, however, to update your mods as you get the opportunity to do so, because not only do the authors fix anything broken, but most authors are also constantly tweaking their mod to make them better.
Q: What's the new toc number? (credit to Cairenn; edits by Syllani)
A: Unless you are a mod author, it doesn't matter. Don’t go in and manually edit your toc numbers; don’t use a toc auto-updater program! There is simply no need. Use the "Load Outdated Addons" check box, located under the AddOns button on your Character Select screen instead. Check in at the location where you got your mod(s) from originally over a few days after a patch, to get the properly updated version from the actual mod author.
By going in and changing all the toc numbers yourself, you are completely defeating the entire purpose of them in the first place.
If you use the "Load Outdated AddOns", without making any changes to the toc numbers (ie, the proper way to deal with patch days), then when something stops working, you've got some hope of figuring out which mod(s) aren't working right, since you can go back to the AddOn button on the Character Select screen and see which mods aren't updated yet.
If, however, you go in and manually change all the toc numbers, so far as WoW is concerned, they are all "current". Now what do you do when they stop working? When all of a sudden you've got error messages popping up all over the place? How do you know which ones are actually current and which ones are outdated and probably the problem? You've no way to tell any more. Leave your toc numbers alone.