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Issue Outlook error 0x800ccc1a after "synching" TLS cyphers

C

Ch3vr0n

Basic Pleskian
Server operating system version
AlmaLinux 8.6 (Sky Tiger)
Plesk version and microupdate number
18.0.44 Update 3
While doing some routine maintenance on my server, i checked things in SSL it! and saw that the last cypher sync was from january last year. Current settings are "Modern" and everything worked fine up until the sync. After the sync i just did, outlook refuses to connect over secure ports and i need to drop the preset down to "intermediate" and everything immediately starts working again.

As it serves no purpose to support old browsers and clients (and inhibits moving forward) i'd like to be able to change back to "modern". I even reissued all new let's encrypt certificates with no effect to the problem.

Why is this happening, what's the fix and what can i do to prevent it?
 
As a solution for this problem on windows 11 i do one of the following:
1st solution: I removed windows update with code 5018418 or better you have search for update with code 50184XX
this solve the problem but you have disable windows updates

2nd solution: I installed 22h2. After installation i was still had the same problem. I checked again for updates and it's fount an update with code 5018493. After installed this update the problem solved.
 
1st reply 4 months. Guess this forum isn't super active. Totally forgot about this.

1st & 2nd solution: that's not a solution, that's avoiding the problem. I am not compromising my system security by uninstalling security updates.
 
Ch3vr0n said:
1st reply 4 months. Guess this forum isn't super active. Totally forgot about this.

1st & 2nd solution: that's not a solution, that's avoiding the problem. I am not compromising my system security by uninstalling security updates.
Click to expand...
I agree for the first solution. It's not secured.

The second solution has no uninstalling anything. After installing 22H2 update problem has not solved. Outllok couln't send email using SSL ot TLS. So i checked again for updates and it's found the 5018493 update. After installation of this update the problem solved and outllok can send messages using TLS or SSL. Sorry for my english.

Do you have solve your problem?
 
Ch3vr0n said:
Guess this forum isn't super active.
Click to expand...
Sorry to read that you have this impression of the forum. Actually, your post was about a Microsoft issue, so probably it would have gotten a better and more feedback in a Microsoft-related forum. The forum here is populated by many experts who review new posts at least daily. But sometimes a topic might not exactly fit to what this forum focuses on.

I am aware that is can be confusing and it can be a demanding task to sort out whether it is a server-side issue or a client-side issue. Mostly if things are Plesk related or server-side issue, many knowledgeable users on this forum will respond with helpful hints promptly. However, if something is client-related, only some users might experience the same and may not be the right experts to talk to as the focus of this forum is on Plesk and not so much on Outlook.

Questions are still welcome, because all is linked with each other. Please continue to contribute, and again, questions are welcome and will normally be reviewed by many experts on here quickly.
 
Ugh again no mail from the forum. Sorry for the delay. Outlook is indeed by microsoft, but TLS type is managed at the plesk level, hence coming here. No clue why it worked before, then stopped working and only works if i drop the TLS level. If mods think there's a better place, i'm open to get it moved off course, still waiting on a proper fix too. I'm not removing windows security updates.
 
"lowering" the TLS level helps circumvent the problem, because it allows the client to fall back to a different (normally "less" secure) cipher.

Microsoft seems to have broken something with cipher suites on this update and TLS connections using these ciphers will fail.
If the server does not offer any ciphers that are not affected by this problem/bug of Windows, then the whole TLS connection will fail.

That being said, Plesk can and will not do anything to fix this problem. It does not make sense to change anything on the server side if nothing is broken there.

And if I may also make another statement regarding this topic - the way Plesk works, it's detrimental to the "security" of email, to configure any TLS compatibility level higher than "old" ...
 
Guess i'll have to leave it on intermediate then. Cause i'm running W11 22H2, outlook fully up to date and modern still won't work.
 
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