Undefined constant "SIGCLD" when upgrading from Nextcloud 26.0.1.1 to 26.0.2.1

[nimra98]

Steps to reproduce

1. Running instance on 26.0.2.1 with Snappymail 2.28.0
2. Try to upgrade to 26.0.2.1 through Docker container change OR console with docker compose exec --user www-data app php occ upgrade
3. Error message is displayed and upgrade fails. Maintenance mode is kept active.

Expected behavior

Smooth upgrade run

Actual behavior

#docker compose exec --user www-data app php occ upgrade
WARN[0000] network web-proxy: network.external.name is deprecated. Please set network.name with external: true 
Nextcloud or one of the apps require upgrade - only a limited number of commands are available
You may use your browser or the occ upgrade command to do the upgrade
Setting log level to debug
Updating database schema
Updated database
Updating <snappymail> ...
An unhandled exception has been thrown:
Error: Undefined constant "SIGCLD" in /var/www/html/custom_apps/snappymail/app/snappymail/v/2.28.0/app/libraries/MailSo/Log/Logger.php:78
Stack trace:
#0 /var/www/html/custom_apps/snappymail/app/snappymail/v/2.28.0/app/libraries/MailSo/Log/Logger.php(78): constant('SIGCLD')
#1 /var/www/html/custom_apps/snappymail/app/snappymail/v/2.28.0/app/libraries/RainLoop/Api.php(64): MailSo\Log\Logger->__construct(true)
#2 /var/www/html/custom_apps/snappymail/app/snappymail/v/2.28.0/app/libraries/RainLoop/Actions.php(120): RainLoop\Api::Logger()
#3 /var/www/html/custom_apps/snappymail/app/snappymail/v/2.28.0/app/libraries/RainLoop/Api.php(12): RainLoop\Actions->__construct()
#4 /var/www/html/custom_apps/snappymail/lib/Migration/InstallStep.php(72): RainLoop\Api::Actions()
#5 /var/www/html/lib/private/Repair.php(126): OCA\SnappyMail\Migration\InstallStep->run(Object(OC\Repair))
#6 /var/www/html/lib/private/legacy/OC_App.php(1077): OC\Repair->run()
#7 /var/www/html/lib/private/legacy/OC_App.php(1019): OC_App::executeRepairSteps('snappymail', Array)
#8 /var/www/html/lib/private/Updater.php(360): OC_App::updateApp('snappymail')
#9 /var/www/html/lib/private/Updater.php(272): OC\Updater->doAppUpgrade()
#10 /var/www/html/lib/private/Updater.php(140): OC\Updater->doUpgrade('26.0.2.1', '26.0.1.1')
#11 /var/www/html/core/Command/Upgrade.php(225): OC\Updater->upgrade()
#12 /var/www/html/3rdparty/symfony/console/Command/Command.php(255): OC\Core\Command\Upgrade->execute(Object(Symfony\Component\Console\Input\ArgvInput), Object(Symfony\Component\Console\Output\ConsoleOutput))#13 /var/www/html/3rdparty/symfony/console/Application.php(1009): Symfony\Component\Console\Command\Command->run(Object(Symfony\Component\Console\Input\ArgvInput), Object(Symfony\Component\Console\Output\ConsoleOutput))
#14 /var/www/html/3rdparty/symfony/console/Application.php(273): Symfony\Component\Console\Application->doRunCommand(Object(OC\Core\Command\Upgrade), Object(Symfony\Component\Console\Input\ArgvInput), Object(Symfony\Component\Console\Output\ConsoleOutput))
#15 /var/www/html/3rdparty/symfony/console/Application.php(149): Symfony\Component\Console\Application->doRun(Object(Symfony\Component\Console\Input\ArgvInput), Object(Symfony\Component\Console\Output\ConsoleOutput))
#16 /var/www/html/lib/private/Console/Application.php(211): Symfony\Component\Console\Application->run(Object(Symfony\Component\Console\Input\ArgvInput), Object(Symfony\Component\Console\Output\ConsoleOutput))
#17 /var/www/html/console.php(100): OC\Console\Application->run()
#18 /var/www/html/occ(11): require_once('/var/www/html/c...')
#19 {main}

Mail app version

not installed. Snappymail: 2.28.0

Mailserver or service

Yahoo

Operating system

Official Nextcloud docker image (nextcloud:26-fpm-alpine)

PHP engine version

PHP 8.2

Web server

Nginx

Database

MariaDB

Additional info

No response

[nimra98]

The issue persists even after disabling Snappymail, upgrading and then trying to re-enabled the app.

[ChristophWurst]

app/snappymail.

please report it to the snappymail maintainers