I have recovered VM backup from date before upgrade with no winbind errors, than upgraded packages with apt. This resulted situation that I described before
I have manually downgraded this packages to previous versions: samba-common_4.2.10+dfsg-0+deb8u2_all.deb samba_4.2.10+dfsg-0+deb8u2_i386.deb samba-common-bin_4.2.10+dfsg-0+deb8u2_i386.deb winbind_4.2.10+dfsg-0+deb8u2_i386.deb libwbclient0_4.2.10+dfsg-0+deb8u2_i386.deb python-samba_4.2.10+dfsg-0+deb8u2_i386.deb samba-vfs-modules_4.2.10+dfsg-0+deb8u2_i386.deb samba-dsdb-modules_4.2.10+dfsg-0+deb8u2_i386.deb samba-libs_4.2.10+dfsg-0+deb8u2_i386.deb and proxy start to work again without segfault errors. This system is quite old and may have some workarounds regarding samba issues in the past (like this one https://bugs.launchpad.net/ubuntu/+source/apache-mod-auth-ntlm-winbind/+bug/1304953) Regards rop
