This just happened on my Arch server (current) (NC 21.0.0.18, NGINX+PHP 8.0.2(php-fpm), MariaDB) installation (as webserver user) when trying to follow instructions to install the files HPB:
$ php occ app:install notify_push
An unhandled exception has been thrown:
TypeError: substr(): Argument #3 ($length) must be of type ?int, bool given in /server/test/apps/notify_push/lib/SetupWizard.php:84
Stack trace:
#0 /server/test/apps/notify_push/lib/SetupWizard.php(84): substr()
#1 /server/test/apps/notify_push/lib/Migration/Install.php(42): OCA\NotifyPush\SetupWizard->testBinary()
#2 /server/test/lib/private/Repair.php(117): OCA\NotifyPush\Migration\Install->run()
#3 /server/test/lib/private/legacy/OC_App.php(1054): OC\Repair->run()
#4 /server/test/lib/private/Installer.php(175): OC_App::executeRepairSteps()
#5 /server/test/core/Command/App/Install.php(68): OC\Installer->installApp()
#6 /server/test/apps/mail/vendor/symfony/console/Command/Command.php(255): OC\Core\Command\App\Install->execute()
#7 /server/test/apps/mail/vendor/symfony/console/Application.php(971): Symfony\Component\Console\Command\Command->run()
#8 /server/test/apps/mail/vendor/symfony/console/Application.php(290): Symfony\Component\Console\Application->doRunCommand()
#9 /server/test/apps/mail/vendor/symfony/console/Application.php(166): Symfony\Component\Console\Application->doRun()
#10 /server/test/lib/private/Console/Application.php(215): Symfony\Component\Console\Application->run()
#11 /server/test/console.php(100): OC\Console\Application->run()
#12 /server/test/occ(11): require_once('...')
#13 {main}http@server /server/test
$ php occ app:install notify_push
notify_push already installed
So, it WAS installed the first time, but what error is that?