Using Thunderbird, with lightning and a Nextcloud calendar? Invites are added to your calendar but no reply is sent to the organizer?

Events and Tasks > Calendar

Right Click on Calendar > Properties > Email > [X] Prefer client-side email scheduling

https://support.mozilla.org/en-US/kb/enable-email-invitations-caldav-servers-configured

Running your own docker based Collabora Online server? Getting 404s after an update with these log entries:

https://.../browser/.../cool.html?WOPISrc=...

Seems like some URLs where changed:

Seems like /loleaflet has been renamed to /browser and lool to cool in latest collabora version.

See #1904 and Proxy Settings.

Having /var/lib/mysql on a separate partition? MariaDB thinks lost+found is a Database? Create /etc/mysql/conf.d/ignore.cnf with

[mysqld]
ignore-db-dir=lost+found

Restart MariaDB and drop the database:

drop database `lost+found`;

Performing a minimal Ubuntu 20.04 install on a server? Black screen after rebooting? Switch to console via ALT+F1 and change in /etc/default/grub

GRUB_CMDLINE_LINUX_DEFAULT="quiet"
GRUB_TERMINAL=console

Run update-grub and reboot.

Seeing

[ssl:warn] … AH01909: $HOSTNAME:443:0 server certificate does NOT include an ID which matches the server name

in your log? Check for any _default_ VirtualHosts:

<VirtualHost _default_:443>

Is your unreclaimable SLAB usage on CentOS 8 growing when running the Check_MK agent on it? See Werk#10070

We have seen cases in which the parameter “KillMode=process” of the unit file “check_mk@.service” causes a memory leak. […] To fix this, the parameter “KillMode=process” was changed to “Type=forking”.

Also systemd#6567 and debian#940021.

On Windows, and need to generate a certificate chain to a server? This script creates one file per certificate in the chain:

$destination = 'foo'

$webRequest = [Net.WebRequest]::Create(https:// + $destination)
$webRequest.AllowAutoRedirect = $FALSE
$webRequest.Method = 'HEAD'
$webRequest.Timeout = 1000

try {
    "Connecting to $destination... " | Write-Host -NoNewline
    $webRequest.GetResponse().HResult | Write-Host
}
catch [System.Net.WebException] {
    $_.Exception.Status | Write-Host

    if ( $_.Exception.Status -ne 'Timeout' ) {
        throw $_
    }
}

"Building certificate chain..." | Write-Host
$chain = New-Object -TypeName System.Security.Cryptography.X509Certificates.X509Chain
$chain.build( $webRequest.ServicePoint.Certificate ) | Out-Null

$contentType = [Security.Cryptography.X509Certificates.X509ContentType]::Cert

"Saving..." | Write-Host
# Skip server certificate
$chain.ChainElements.Certificate | Select-Object -Skip 1 | ForEach-Object {
    set-content `
        -value $( $_.Export( $contentType  ) ) `
        -path "$pwd\$( $_.Thumbprint ).cer" `
        -encoding byte

    $_
} | Format-Table | Out-String | Write-Host

Playing with FreeIPA? Recreating the CA? Firefox complaining about SEC_ERROR_REUSED_ISSUER_AND_SERIAL? Can’t find the certificate via Preferences / Privacy & Security / Certificates?

Try deleting it via CLI:

certutil -L -d <folder/to/cert8.db> | grep -i ipa
certutil -D -d <folder/to/cert8.db> -n <nickname>

Migrating from MySQL to MariaDB on Ubuntu? MariaDB not starting? There may be an old AppArmor Profile in the way. Or mysql.service and mariadb.service may both be enabled.

Trying to talk to AD via ldaps:// and -Y GSSAPI? Getting

sb_sasl_generic_pkt_length: received illegal packet length of 813957120 bytes

According to Microsofts Open Specification: 5.1.1.1.2 SASL Authentication:

While Active Directory permits SASL binds to be performed on an SSL/TLS-protected connection, it does not permit the use of SASL-layer encryption/integrity verification mechanisms on such a connection.

Also passing -O "maxssf=0,minssf=0" to ldapsearch works for me.

See redhat:4661861, lp:#1015819, cyrus-sasl:#419, cyrus-sasl:#603.