Addon restrictions in WoW Forever explained

In short

• Addons are allowed, and most work normally: quest helpers, maps, bags, Auction House, tooltips, boss mods.
• What's locked is mainly combat data. Addons that track or display every hit don't work, or only partially.
• A damage meter, a cooldown manager and a swing timer are built into the game. per fan sites

What is locked

• Combat log: The combat log records every hit, heal and spell. In Forever, addons no longer have access to it. It used to be the backbone of damage meters and combat text addons. per fan sites
• Secret values: In combat, values like an enemy's health are “secret” to addons. An addon can display them but can't do math with them or make decisions based on them. per fan sites
• Automation: Casting, targeting and moving via addons have never been allowed and remain locked. Addons show you information, but they don't play for you.

These rules come from retail and apply to Forever as well. Blizzard wants to stop addons from solving fights for you.

What this means for you

• Damage meters: Meters that read the combat log show nothing or wrong numbers. Use the built-in damage meter or an addon specifically updated for Forever.
• Combat text: Floating combat text from addons like MSBT or EavesDrop needs the combat log, so it doesn't work.
• WeakAuras: There's no official Forever version. Avoid unofficial ports from unknown sources. They may contain bugs or malware.
• Boss mods: DBM is officially maintained for Forever, and players report that BigWigs works too.
• Everything else: Quest, map, bag, Auction House and profession addons are not affected.

Check the Compatibility list for the current status of the most popular addons.

Other beta quirks

• Retail addons: Players report that Forever also loads addons and key bindings from retail. This is disputed. Keep the folders separate. per fan sites
• Settings: Settings are sometimes lost after /reload. Back up the WTF folder. per fan sites
• Version: Forever addons use interface version 16001. The game only loads older addons with the “Load out of date AddOns” option.

Beta path: _classic_beta_\Interface\AddOns (may change at launch).

See the Installation guide for how to install addons correctly.