WowAce

(Is this still the right spot to report issues?)

The options panel templates were removed in 1.15.4 (the current classic era PTR). This is preventing LibKeyBound from loading. To fix:

1. Delete the following line:

local WoW10 = select(4, GetBuildInfo()) >= 100000

2. Replace this:

WoW10 and 'UICheckButtonTemplate' or 'OptionsCheckButtonTemplate'

With this:

'UICheckButtonTemplate'

3. Finally, replace this:

WoW10 and 'UIPanelButtonTemplate' or 'OptionsButtonTemplate'

With this:

'UIPanelButtonTemplate'

Went ahead and resolved this in r126.

Checked the changes on all Classic clients prior to doing so and everything looked like it worked fine - all of the "WoW10"-specific templates are defined in both current Classic (4.4.0) and Classic Era (1.15.3) clients and there's no errors using them.