DN index delete failed

My syncrepl provider seems to be missing updates following an upgrade to 2.3.40. While I was trying to push them through this morning, I got an odd message:

Jan 28 08:46:19 slapd[12685]: [ID 588225 local4.debug] conn=234174 op=2 RESULT tag=107 err=80 text=DN index delete failed

Is there anything I can do about this, or maybe just an idea of where to look or what information to take down for next time? I was going to try and file an ITS for tracking or maybe to try and walk some structures, but the DN in question deleted without incident about ten minutes later.