An abbreviation of 'trouble' meaning a problem, malfunction, or other issue; a colloquial term often used for work-related incidents.
現場でトラが出て、作業を一時中断した。
A trouble occurred on site, and work was temporarily suspended.
納品直前にトラが見つかり、対応に追われた。
A problem was found just before delivery, and we were busy dealing with it.
パソコンにトラが発生してログインできない。
A problem occurred with the computer and I can't log in.