It's probably related to the apache change that the plesk team is working on releasing an actual patch but for now there is a work on.
Refer to this post:
Issue - 421 Misdirected Request
for fix CVE-2025-23048 the SSLStrictSNIVHostCheck directive is now enabled by default and proxy must send host to apachetalk.plesk.com
Has anyone managed to get Activesync working on their server after the Apache bug? Issue - 421 Misdirected Request patch does not resolve the error.
Or if anyone knows which log to look at
Misdirected Request
The client needs a new connection for thisrequest as the requested host name does not matchthe Server Name Indication (SNI) in use for thisconnection.
Apache Server at webmail.**domain** Port 443
Mozilla Thunderbird2025.07.18 23:25:49 **email** Synch operation started (flags = 00000031)
2025.07.18 23:25:49 **email** StartImport(flags = 00000000, max msg = ffffffff): full items
2025.07.18 23:25:49 **email** EnsureProtoInfo: Error getting remote URL (hr = 0x80070057)
2025.07.18 23:25:49 **email** Unable to parse URL for protocol handler:
Communications error (HTTP status 421)
mv /etc/nginx/conf.d/fixssl.conf /etc/nginx/conf.d/fixssl.conf-old
plesk repair web -y
No, no change.Guys, it was confirmed that the workaround previously suggested for the Apache update is indeed causing an issue of ActiveSync and IMAP connectivity with Plesk Premium Email. The workaround we can suggest is:
- Connect to the server via SSH.
- Rename the file deployed by the hotfix:
Bash:mv /etc/nginx/conf.d/fixssl.conf /etc/nginx/conf.d/fixssl.conf-old
- Regenerate the web server configuration:
Bash:plesk repair web -y
@Compy can you please confirm if that solves the issue for you? Thank you in advance.
The log is empty. console.log empty, only the sendmail.log is used.& if that doesn't work, check the error log for ActiveSync here:
/var/log/kolab-syncroton/errors.log
I had my own dramas on a 20.04 LTS server after updating kolab/roundcube resulting in missing columns in the roundcube SQL database (was causing 500 errors in the domain's NGINX log for both sync and ping AS commands from the client).
It was all resolved simply by adding back the two missing columns that were reported missing in the errors.log.
Even if your issue isn't the same, it's the errors.log file that will most likely reveal the reason your AS isn't working.
webCheck the domain's nginx log for any entries related to a client connecting to AS. Filter by "ActiveSync".
You should at least see some POST requests reaching the server.
If not, then the client might need inspection (a firewall on the client computer or possibly on the server)
proxy_access_ssl_log**IP** - - [22/Jul/2025:14:37:17 +0200] "GET /Autodiscover/Autodiscover.xml HTTP/2.0" 421 389 "-" "Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:140.0) Gecko/20100101 Firefox/140.0"
Mozilla Thunderbird TbSync**IP** - **mail** [22/Jul/2025:06:47:32 +0200] "POST /Microsoft-Server-ActiveSync?Cmd=FolderSync&User=**mail**&DeviceId=**ID**&DeviceType=WindowsOutlook15 HTTP/1.1" 421 389 "-" "Outlook/15.0 (15.0.5337.1000; MSI; x64)"
**IP** - **mail** [22/Jul/2025:14:38:59 +0200] "POST /Microsoft-Server-ActiveSync?Cmd=Settings&User=**mail**&DeviceType=TbSync&DeviceId=**id** HTTP/2.0" 421 389 "-" "Thunderbird ActiveSync"
2025/07/22 09:38:06 [error] 38537#0: *4085 open() "/var/www/vhosts/**domain**/httpdocs/favicon.ico" failed (2: No such file or directory), client: **ip**, server: **domain**, request: "GET /favicon.ico HTTP/2.0", host: "**domain**", referrer: "https://**domain**/Autodiscover/Autodiscover.xml"
Guys, it was confirmed that the workaround previously suggested for the Apache update is indeed causing an issue of ActiveSync and IMAP connectivity with Plesk Premium Email. The workaround we can suggest is:
- Connect to the server via SSH.
- Rename the file deployed by the hotfix:
Bash:mv /etc/nginx/conf.d/fixssl.conf /etc/nginx/conf.d/fixssl.conf-old
- Regenerate the web server configuration:
Bash:plesk repair web -y
@Compy can you please confirm if that solves the issue for you? Thank you in advance.
Checking web server configuration. Please wait
will fix the sites again, not the ActiveSync error.echo -e "proxy_ssl_server_name on;\nproxy_ssl_name \$host;\nproxy_ssl_session_reuse off;" > /etc/nginx/conf.d/fixssl.conf && systemctl restart nginx