Hello OpenLDAP-Technical,
I am running slamd tests against OpenLDAP 2.4.44 (RHEL7; client is RHEL shop so stuck for now at this version). I realize that olcThreads: 128 is probably overkill for most systems, but when I tried it, I got the captioned error. The max that olcThreads can be set to it seems is 128 minus the number of syncrepls you have. Otherwise it looks like that with enough client connections, this error will happen, and operations will fail err=80 (internal error).