ESO Subclassing Locked warnings usually come from the three-slot account-wide training limit, a line that hasn’t reached rank 50, or one of the class-combination rules. Unlocking A Study in Discipline doesn’t remove those limits.
If the menu won’t let you replace your last subclass line or shows 3/3, don’t waste a respec scroll trying to force it. Here’s how to tell which rule is stopping the swap and how to make room for a new line.
Why a subclass training slot stays locked
Every unmastered subclass line reserves one of three training slots across the account. A locked slot often means you’re already training the maximum number of new lines. A different character can’t free that commitment just by unequipping the same line. The line must reach skill-line rank 50 to become mastered; after that it no longer occupies an unfinished training slot. Check the rank in Skills → Subclassing rather than your character’s level.
How to master a Subclassing skill line
Equip a subclass line you’re currently training and keep using a build that lets you progress the line towards rank 50. Its progress is shared with that same subclass line on other characters, allowing you to continue training on another character rather than starting from zero. When you hit rank 50, the account gets the corresponding mastered collectible. Once you master that line, its training slot is freed and you can begin levelling another class line.
What the gold plus and ribbon mean
In the Subclassing menu, an unmastered line can display a ribbon when you select it for training. Mastered lines and lines you are already actively training display an Equip option with a golden plus. Don’t confuse Equip with beginning a new subclass. A Study in Discipline needs the new subclass action to satisfy its quest step. If your quest won’t advance, make sure you picked a line your account hasn’t mastered and selected the Subclass action rather than Equip.
Check the one-native-line rule
You cannot remove all three original class lines from your character. Keep one native line equipped, then add no more than two borrowed lines from two different outside classes. If you’re already using a Warden line on a Dragonknight, another Warden line won’t be available as your second outside-class choice. That’s a class-combination restriction, not a broken training slot. Check the message shown when you try to confirm your choice.
If the subclassing menu is missing
A Study in Discipline must be unlocked after at least one character reaches level 50. Start it through Quest Starters, the Skills menu or Bahtra at-Hunding near the wayshrines in Riften, Evermore or Dune. Talk to her, choose ‘Choose Disciplines: Free’, subclass an unmastered line and equip its first skill, then return to Bahtra. If the menu never appears, finish the introductory quest first. You can’t unlock it simply by resetting ordinary skills.
Does a respec remove the lock?
Free skill respecs arrived in Update 49 and the Armory can restore saved line arrangements, but neither one awards a missing rank-50 mastery. If your three training slots are occupied, reallocating ordinary Skill Points does not make a new unmastered line available. Similarly, a Class Mastery passive is separate from the subclass-training system. If you’re at the 3/3 training cap, one of those three lines has to reach rank 50 before you can start another.
Update 50 and a wrongly occupied slot
ZeniMax fixed a bug in Update 50 that kept mastered subclassing lines from being removed correctly on other characters. If the subclass line still appears locked despite the skill line showing rank 50, install the latest update and check that its mastery collectible is present. Note the specific line, all affected characters, platform and whether the menu says Equip or Subclass. A persistent incorrect account-wide count deserves a support report rather than risky character deletion.
What to choose next
Once a line is mastered, open Skills → Subclassing and choose your next unmastered line if you still want another character skill set. You can also equip an already-mastered line immediately without using a training slot. Mastered lines can be equipped again without using a training slot, while unmastered lines continue occupying a slot until rank 50. The best way to avoid filling all three slots accidentally is to check the ribbon and confirm screen before starting training.
Related ESO Subclassing Locked Guides
Official source: ESO Support skill-system guide.
