This change will be deployed to WMF wikis with 1.24wmf7, see Gerrit change 135283
will cause action=logevents to return an error if both the letitle and leprefix parameters are specified. Previously specifying both of these parameters would apply both filters, making leprefix pointless if letitle matches the prefix or returning no results if not.
The expected impact of this change is low, as no uses of this parameter combination were logged in the time period checked.
If any client is affected by this change, it may simply remove leprefix when letitle is specified.