Error 500 - After upgrade

[Metreas]

Hello,

after an upgrade from 2.3.8 to 2.3.9 and set of smtp port in .env I recieved an Error 500.

.env-file

APP_ENV=production
APP_DEBUG=false
APP_URL=https://cachet.studydev.de
APP_KEY=base64:****=

DB_DRIVER=mysql
DB_HOST=****
DB_DATABASE=****
DB_USERNAME=****
DB_PASSWORD=****
DB_PORT=3306
DB_PREFIX=null

CACHE_DRIVER=apc
SESSION_DRIVER=apc
QUEUE_DRIVER=sync
CACHET_EMOJI=false

MAIL_DRIVER=smtp
MAIL_HOST=mail.studydev.de
MAIL_PORT=25
MAIL_USERNAME=****
MAIL_PASSWORD=****
MAIL_ADDRESS=****
MAIL_NAME=****
MAIL_ENCRYPTION=tls

REDIS_HOST=null
REDIS_DATABASE=null
REDIS_PORT=null

GITHUB_TOKEN=null

This error was shown after start "php artisan app:update":

PHP Fatal error:  Uncaught ErrorException: count(): Parameter must be an array or an object that implements Countable in /var/www/sites/cachet/vendor/graham-campbell/exceptions/src/ExceptionIdentifier.php:51
Stack trace:
#0 [internal function]: Illuminate\Foundation\Bootstrap\HandleExceptions->handleError(2, 'count(): Parame...', '/var/www/sites/...', 51, Array)
#1 /var/www/sites/cachet/vendor/graham-campbell/exceptions/src/ExceptionIdentifier.php(51): count(NULL)
#2 /var/www/sites/cachet/vendor/graham-campbell/exceptions/src/ExceptionHandlerTrait.php(47): GrahamCampbell\Exceptions\ExceptionIdentifier->identify(Object(ErrorException))
#3 /var/www/sites/cachet/bootstrap/cache/compiled.php(2163): GrahamCampbell\Exceptions\ExceptionHandler->report(Object(ErrorException))
#4 [internal function]: Illuminate\Foundation\Bootstrap\HandleExceptions->handleException(Object(ErrorException))
#5 {main}
  thrown in /var/www/sites/cachet/vendor/graham-campbell/exceptions/src/ExceptionIdentifier.php on line 51
PHP Fatal error:  Uncaught ErrorException: count(): Parameter must be an array or an object that implements Countable in /var/www/sites/cachet/vendor/graham-campbell/exceptions/src/ExceptionIdentifier.php:51
Stack trace:
#0 [internal function]: Illuminate\Foundation\Bootstrap\HandleExceptions->handleError(2, 'count(): Parame...', '/var/www/sites/...', 51, Array)
#1 /var/www/sites/cachet/vendor/graham-campbell/exceptions/src/ExceptionIdentifier.php(51): count(NULL)
#2 /var/www/sites/cachet/vendor/graham-campbell/exceptions/src/ExceptionHandlerTrait.php(47): GrahamCampbell\Exceptions\ExceptionIdentifier->identify(Object(Symfony\Component\Debug\Exception\FatalErrorException))
#3 /var/www/sites/cachet/bootstrap/cache/compiled.php(2163): GrahamCampbell\Exceptions\ExceptionHandler->report(Object(Symfony\Component\Debug\Exception\FatalErrorException))
#4 /var/www/sites/cachet/bootstrap/cache/compiled.php(2181): Illuminate\Foundation\Bootstrap\HandleExceptions->handleException(Object(Symfony\Component\Debug\Exception\FatalErrorExcepti in /var/www/sites/cachet/vendor/graham-campbell/exceptions/src/ExceptionIdentifier.php on line 51

Unfortunately, this problem is completely unknown to me. Could you help, please?

[Metreas]

Sry wrong project