Hi All! I would appreciate any clue to solve the problem we are having with a client mode service that stopped working this week (we verified that the service works directly without stunnel). The error I identify in the trace is the following: "TLS alert (write): fatal: decode error" Stunnel Config (windows version): [afip-prod-fce] client = yes accept = ARSASSRV4DMS06:1031 connect = serviciosjava.afip.gob.ar:443 debug = 7 ws: https://serviciosjava.afip.gob.ar/wsfecred/FECredService Complete trace: 2024.01.24 09:28:46 LOG5[main]: stunnel 5.71 on x64-pc-mingw32-gnu platform 2024.01.24 09:28:46 LOG5[main]: Compiled/running with OpenSSL 3.1.3 19 Sep 2023 2024.01.24 09:28:46 LOG5[main]: Threading:WIN32 Sockets:SELECT,IPv6 TLS:ENGINE,OCSP,PSK,SNI 2024.01.24 09:28:46 LOG5[main]: Reading configuration from file C:\Program Files (x86)\stunnel\config\stunnel.conf 2024.01.24 09:28:46 LOG5[main]: UTF-8 byte order mark detected 2024.01.24 09:28:46 LOG5[main]: FIPS mode disabled 2024.01.24 09:28:46 LOG4[main]: Service [afip-prod-fce] needs authentication to prevent MITM attacks 2024.01.24 09:28:46 LOG5[main]: Configuration successful 2024.01.24 09:29:23 LOG7[0]: Service [afip-prod-fce] started 2024.01.24 09:29:23 LOG7[0]: Setting local socket options (FD=892) 2024.01.24 09:29:23 LOG7[0]: Option TCP_NODELAY set on local socket 2024.01.24 09:29:23 LOG5[0]: Service [afip-prod-fce] accepted connection from 10.70.162.24:57723 2024.01.24 09:29:23 LOG6[0]: s_connect: connecting 200.1.116.19:443 2024.01.24 09:29:23 LOG7[0]: s_connect: s_poll_wait 200.1.116.19:443: waiting 10 seconds 2024.01.24 09:29:23 LOG7[0]: FD=896 ifds=rwx ofds=--- 2024.01.24 09:29:24 LOG5[0]: s_connect: connected 200.1.116.19:443 2024.01.24 09:29:24 LOG5[0]: Service [afip-prod-fce] connected remote server from 10.72.0.69:64788 2024.01.24 09:29:24 LOG7[0]: Setting remote socket options (FD=896) 2024.01.24 09:29:24 LOG7[0]: Option TCP_NODELAY set on remote socket 2024.01.24 09:29:24 LOG7[0]: Remote descriptor (FD=896) initialized 2024.01.24 09:29:24 LOG6[0]: SNI: sending servername: serviciosjava.afip.gob.ar 2024.01.24 09:29:24 LOG6[0]: Peer certificate not required 2024.01.24 09:29:24 LOG7[0]: TLS state (connect): before SSL initialization 2024.01.24 09:29:24 LOG7[0]: Initializing application specific data for session authenticated 2024.01.24 09:29:24 LOG7[0]: TLS state (connect): SSLv3/TLS write client hello 2024.01.24 09:29:24 LOG7[0]: TLS state (connect): SSLv3/TLS write client hello 2024.01.24 09:29:24 LOG7[0]: TLS state (connect): SSLv3/TLS read server hello 2024.01.24 09:29:24 LOG6[0]: CERT: Certificate verification disabled 2024.01.24 09:29:24 LOG6[0]: CERT: Certificate verification disabled 2024.01.24 09:29:24 LOG6[0]: CERT: Certificate verification disabled 2024.01.24 09:29:24 LOG7[0]: TLS state (connect): SSLv3/TLS read server certificate 2024.01.24 09:29:24 LOG7[0]: TLS state (connect): SSLv3/TLS read server key exchange 2024.01.24 09:29:24 LOG7[0]: OCSP stapling: Client callback called 2024.01.24 09:29:24 LOG6[0]: OCSP: Certificate chain verification disabled 2024.01.24 09:29:24 LOG6[0]: Client certificate not requested 2024.01.24 09:29:24 LOG7[0]: TLS state (connect): SSLv3/TLS read server done 2024.01.24 09:29:24 LOG7[0]: TLS state (connect): SSLv3/TLS write client key exchange 2024.01.24 09:29:24 LOG7[0]: TLS state (connect): SSLv3/TLS write change cipher spec 2024.01.24 09:29:24 LOG7[0]: TLS state (connect): SSLv3/TLS write finished 2024.01.24 09:29:24 LOG7[0]: TLS state (connect): SSLv3/TLS write finished 2024.01.24 09:29:24 LOG7[0]: TLS state (connect): SSLv3/TLS read change cipher spec 2024.01.24 09:29:24 LOG7[0]: TLS state (connect): SSLv3/TLS read finished 2024.01.24 09:29:24 LOG7[0]: New session callback 2024.01.24 09:29:24 LOG7[0]: Peer certificate was cached (6643 bytes) 2024.01.24 09:29:24 LOG6[0]: Session id: D63C79766AC02C9A3E8494AD528954A183E9F7C250856695BA05C16A2219A4B3 2024.01.24 09:29:24 LOG7[0]: 1 client connect(s) requested 2024.01.24 09:29:24 LOG7[0]: 1 client connect(s) succeeded 2024.01.24 09:29:24 LOG7[0]: 0 client renegotiation(s) requested 2024.01.24 09:29:24 LOG7[0]: 0 session reuse(s) 2024.01.24 09:29:24 LOG6[0]: TLS connected: new session negotiated 2024.01.24 09:29:24 LOG6[0]: TLSv1.2 ciphersuite: ECDHE-RSA-AES128-GCM-SHA256 (128-bit encryption) 2024.01.24 09:29:24 LOG6[0]: Peer temporary key: ECDH, P-256, 256 bits 2024.01.24 09:29:24 LOG7[0]: Compression: null, expansion: null 2024.01.24 09:29:24 LOG7[0]: Remove session callback 2024.01.24 09:29:24 LOG7[0]: TLS alert (write): fatal: decode error 2024.01.24 09:29:24 LOG6[0]: TLS socket closed (SSL_read) 2024.01.24 09:29:24 LOG7[0]: Sent socket write shutdown 2024.01.24 09:29:24 LOG5[0]: Connection closed: 1755 byte(s) sent to TLS, 634 byte(s) sent to socket 2024.01.24 09:29:24 LOG7[0]: Remote descriptor (FD=896) closed 2024.01.24 09:29:24 LOG7[0]: Local descriptor (FD=892) closed 2024.01.24 09:29:24 LOG7[0]: Service [afip-prod-fce] finished (0 left) Thank you! Kind regards, Rodrigo.