Claude Code can refuse to use a git worktree, which is an extra working folder attached to the same repository, when it has its own per-worktree config file. The refusal message now gives the command that shows where that file is: git rev-parse --git-path config.worktree. It also warns that sparse-checkout needs that file. Sparse-checkout is a git feature that fills a folder with only part of a repository.
Why
You can locate the file that caused the refusal. You are also warned before deleting it if you rely on sparse-checkout.