Error in sphinx: sort-by attribute 'threadstart' and 'forum' not found

[RedFoxy]

There is a way to fix that error?

Oops! An error occurred: index ThreadPostDelta,ThreadPostMain: sort-by attribute 'threadstart' not found

And that too:

Oops! An error occurred: index ThreadPostDelta,ThreadPostMain: sort-by attribute 'forum' not found