R66 transfers sometimes end with errors about rule ID not set

This is a received file.

Here is the resulting transfer, and logs are attached :

$ wg transfer list
Transfers:
● Transfer 1 (as server) [ERROR]
    Remote ID:        5
    Rule:             config_gw_2
    Requester:        wmserver
    Requested:        gw-r66
    True filepath:    /var/lib/waarp-gateway/work/gw-20201130003307.zip.tmp
    Source file:      gw-20201130003307.zip
    Destination file: gw-20201130003307.zip
    Start time:       2020-11-30T00:34:20Z
    Step:             
    Progress:         4635
    Task number:      0
    Error message:    I: internal database error

error.log