wire protocol errors on Debian (py3/psyco 2.8)

Hi all,

we have two reports for psycopg2 2.8 under Python 3 on Debian
showing a problem with the wire protocol (full logs appended):

psycopg2.OperationalError: datos insuficientes en el mensaje «T»

or

psycopg2.DatabaseError: el contenido del mensaje no concuerda con el largo, en el mensaje tipo «C»

The error happens at different times when running the same
code. The versions involved:

psycopg2 module version: 2.8.4 (dt dec pq3 ext lo64)
PostgreSQL via DB-API module "<module 'psycopg2' from '/usr/lib/python3/dist-packages/psycopg2/__init__.py'>": API level 2.0, thread safety 2, parameter style "pyformat"
libpq version (compiled in): 120000
libpq version (loaded now) : 120002

Platform: uname_result(system='Linux', node='Epigen7', release='5.4.0-4-amd64', version='#1 SMP Debian 5.4.19-1 (2020-02-13)', machine='x86_64', processor='')

Python 3.7.6 (default, Jan 19 2020, 22:34:52) <\n>[GCC 9.2.1 20200117] on linux (posix)

lsb_release: {'ID': 'Debian', 'OS': 'GNU/Linux', 'DESCRIPTION': 'Debian GNU/Linux bullseye/sid', 'RELEASE': 'testing', 'CODENAME': 'bullseye'}

threading: sys.thread_info(name='pthread', lock='semaphore', version='NPTL 2.29')

We don't yet know the exact version of PostgreSQL this is
running against but it is likely 12.2-1+b1 from
Debian/Unstable.

Any ideas or hints what to look at next ?

Thanks,
Karsten
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