Include 256 in your loglevel, if you haven't already, and look for the
'<date> swizzle slapd[<pid>]: conn=<num> ...' lines it produces.
In particular, look for 'conn=<num> op=<num> RESULT' lines _after_
the 'deferring operation' line, where the matched received operation
(same conn and op) was _before_ that line. Notice what the operation
was, and what the result code was (RESULT ... err=). You'll find the
result code descriptions in RFC 4511.
The examples I could find all look like this:
Apr 11 15:06:43 cliff slapd[15355]: conn=1 op=36051 BIND anonymous
mech=implicit ssf=0
Apr 11 15:06:43 cliff slapd[15355]: conn=1 op=36051 BIND dn="" method=128
Apr 11 15:06:43 cliff slapd[15355]: connection_input: conn=1 deferring
operation: pending operations
Apr 11 15:06:43 cliff slapd[15355]: conn=1 op=36051 RESULT tag=97 err=0 text=
I can't find a reference to '97' anywhere in the above mentioned RFC.
Is there somewhere else I should look?