I'm not having any issue with the signature text being saved.  As mentioned elsewhere I'm finding the at-top signature does not go at-top reliably... but no problem actually setting the signature text itself.

I have seen your remark. Therefore I started testing ...

My recommendation right now: do not forget to take a snapshot before.

If I take my experiences: 3 of 4 will run into this issue!

My SMG update did not mount the vastorage disk after the first reboot.

it mounted after the second reboot 

I too encountered issues after applying this update to my SMG production appliance!

• 23.3.5 had already been applied as well as the OS update. 
• SMG had been running for a couple of weeks without any (noticeable) issues.
• I checked the registration: it was good.
• I applied update 23.3.6. and rebooted.
• After the appliance had restarted, it was essentially dead: no mail flow; no web interface.

Troubleshooting

• /vastorage/smg was empty!
• After a reboot, it was still empty.
• /var/log/messages showed disk errors on sdb1 & sdc1.

Corrective action

• After working many hours with OT support and making no progress, I decided to attempt to resolve the disk errors.
• I was unable to umount /dev/sdc1 
• I did umount /dev/sdb1
• I ran e2fsck /dev/sdb1. It found and repaired dozens of errors. 
• After a reboot, the appliance is once again processing email and I have access to the web interface.

I encountered a different error on my SMGTEST appliance:

I have an SMG appliance which I intended to use to test new patches. It is essentially unconfigured. I thought I might have to deploy it to replace my corrupted production appliance. I hadn't used it in several months.

• Yesterday, I powered it on and saw there was an online update. I did not check carefully to see what it contained.
• The registration had expired so I provided a new key. I now had a valid registration.
• I did the online update and rebooted. All looked good. IIRC, it showed 23.3.6.
• I now had the OS update to install. It completed successfully.
• After the appliance restarted I noticed it showed 23.3.4 rpm:1.0.1-506.1
• The 23.3.6 update was no longer available. I just checked and there are still no updates.

I have opened a case...

Most of us are using SMG Appliances which are running for two or more years and got many updates.

I think it’s a good idea to force a filesystem check before starting the update.

but that can run for hours on big appliances 

Thomas Stimper said:

I think it’s a good idea to force a filesystem check before starting the update.

I think that is a GREAT idea.

You should create an IDEA for that one so I can vote on it! 

SMG applications need to be restarted.  There's a database update required for the signature service, which will prevent changes being saved until the schema is up to date.  Restarting smg-supervisor will apply the schema changes.

There is a fix coming in the next update for the other signature based issues that people have encountered.

Restart did not help in my open cases ...