---
title: "PBS: decryption failed or bad record mac"
url: https://michalasobczak.pl/posts/pbs-decryption-failed-or-bad-record-mac.html
author: "Michał Sobczak"
description: "During sync between two Proxmox Backup Server instances I got “decryption failed or bad record mac” error message. So I decided to go for upgrading source PBS to match its version with target PBS. PBS upgrade To upgrade PBS: Get rid of bookworm sources."
published: 2025-09-27T07:23:57.000Z
updated: 2025-09-27T07:23:57.000Z
language: en
categories: ["Technology"]
tags: ["Proxmox", "Proxmox Backup Server"]
license: CC BY-NC-ND 4.0 (https://creativecommons.org/licenses/by-nc-nd/4.0/)
---
# PBS: decryption failed or bad record mac

During sync between two Proxmox Backup Server instances I got “decryption failed or bad record mac” error message. So I decided to go for upgrading source PBS to match its version with target PBS.

## PBS upgrade

To upgrade PBS:

```bash
apt update
apt dist-upgrade
tar czf "pbs3-etc-backup-$(date -I).tar.gz" -C "/etc" "proxmox-backup"
pbs3to4
proxmox-backup-manager versions
sed -i 's/bookworm/trixie/g' /etc/apt/sources.list
cat > /etc/apt/sources.list.d/proxmox.sources << EOF
Types: deb
URIs: http://download.proxmox.com/debian/pbs
Suites: trixie
Components: pbs-no-subscription
Signed-By: /usr/share/keyrings/proxmox-archive-keyring.gpg
EOF
```

Get rid of bookworm sources. And then:

```bash
apt update
apt dist-upgrade
systemctl reboot
```

However it did not help.

## Further debugging

3 things involved in this investigation.

This one:

```text
ethtool -K eth0 tso off gro off gso off ufo off
```

Next disabling Suricata IDS/ISP. Did not help.

Finally I changed pfSense settings for System – Advanced – Firewall & NAT from Aggressive to Conservative:

![](https://michalasobczak.pl/wp-content/uploads/2025/09/obraz.png)

It worked.