`iperf3: error - unable to receive cookie at server: Bad file descriptor`

With 3.18 I see the errors below, which I hadn’t seen with 3.15 (edit: the second part is wrong: It’s there with 3.15.):

$ iperf3 --version
iperf 3.18 (cJSON 1.7.15)
Linux platsch.molgen.mpg.de 5.15.131.mx64.457 #1 SMP Tue Sep 12 12:55:20 CEST 2023 x86_64
Optional features available: CPU affinity setting, IPv6 flow label, TCP congestion algorithm setting, sendfile / zerocopy, socket pacing, authentication, bind to device, support IPv4 don't fragment, POSIX threads
$ iperf3 --server --port 5201 --bind iperf3.molgen.mpg.de --timestamps
Wed May 14 10:43:57 2025 -----------------------------------------------------------
Wed May 14 10:43:57 2025 Server listening on 5201 (test #1)
Wed May 14 10:43:57 2025 -----------------------------------------------------------
Wed May 14 10:53:28 2025 iperf3: error - unable to receive cookie at server: Bad file descriptor
Wed May 14 10:53:28 2025 -----------------------------------------------------------
Wed May 14 10:53:28 2025 Server listening on 5201 (test #2)
Wed May 14 10:53:28 2025 -----------------------------------------------------------
warning: JSON data length overflow
Wed May 14 10:53:29 2025 iperf3: error - unable to receive parameters from client: Bad file descriptor
Wed May 14 10:53:29 2025 -----------------------------------------------------------
Wed May 14 10:53:29 2025 Server listening on 5201 (test #3)
Wed May 14 10:53:29 2025 -----------------------------------------------------------
warning: JSON data length overflow
Wed May 14 10:53:29 2025 iperf3: error - unable to receive parameters from client: Bad file descriptor
Wed May 14 10:53:29 2025 -----------------------------------------------------------
Wed May 14 10:53:29 2025 Server listening on 5201 (test #4)
Wed May 14 10:53:29 2025 -----------------------------------------------------------