After a NextCloud update you might not be able to load the application again. The browser will load an 502 error page and the logs will show something like this:

Nginx access log:

x.x.x.x - - [12/Oct/2026:06:48:26 +0000] "GET / HTTP/1.1" 502 150 "-" "Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:157.0) Gecko/20100101 Firefox/157.0"

Nginx error log:

2026/10/12 06:48:26 [error] 385#385: *258833 recv() failed (104: Connection reset by peer) while reading response header from upstream, client: x.x.x.x, server: _, request: "GET / HTTP/1.1", upstream: "fastcgi://unix:/run/php/php8.3-fpm.sock:", host: "cloud.example.com"

PHP-FPM log:

[12-Oct-2026 06:48:26] NOTICE: [pool www] child 1000662 started
[12-Oct-2026 06:48:27] WARNING: [pool www] child 1000660 exited on signal 11 (SIGSEGV) after 2.909891 seconds from start

Install xdebug to get relevant information from PHP

# apt install php8.3-xdebug

You don't want to run PHP-FPM with xdebug enabled. Comment ,with ;, zend_extension=xdebug.so in /etc/php/8.3/fpm/conf.d/20-xdebug.ini (or appropriate PHP version)

Once xdebug is installed the segmentation fault is "replaced" with an actual error message.

Your error might differ different, but you now know what the problem is.

php occ -V
An unhandled exception has been thrown:
OCP\Exceptions\AppConfigTypeConflictException: Config value bruteforcesettings/enabled is stored as boolean but was requested as string in /var/www/html/lib/private/AppConfig.php:537
Stack trace:
#0 /var/www/html/lib/private/AppConfig.php(385): OC\AppConfig->getTypedValue()
#1 /var/www/html/lib/private/AppConfig.php(1889): OC\AppConfig->getValueString()
#2 [internal function]: OC\AppConfig->OC\{closure}()
#3 /var/www/html/lib/private/AppConfig.php(1887): array_filter()
#4 /var/www/html/lib/private/Memcache/Factory.php(122): OC\AppConfig->getAppInstalledVersions()
#5 /var/www/html/lib/private/Memcache/Factory.php(163): OC\Memcache\Factory->getGlobalPrefix()
#6 /var/www/html/lib/private/Server.php(936): OC\Memcache\Factory->createLocking()
#7 /var/www/html/lib/private/AppFramework/Utility/SimpleContainer.php(169): OC\Server->OC\{closure}()
#8 /var/www/html/3rdparty/pimple/pimple/src/Pimple/Container.php(122): OC\AppFramework\Utility\SimpleContainer->OC\AppFramework\Utility\{closure}()
#9 /var/www/html/lib/private/AppFramework/Utility/SimpleContainer.php(136): Pimple\Container->offsetGet()
#10 /var/www/html/lib/private/ServerContainer.php(154): OC\AppFramework\Utility\SimpleContainer->query()
#11 /var/www/html/lib/private/AppFramework/Utility/SimpleContainer.php(45): OC\ServerContainer->query()
#12 /var/www/html/lib/private/Files/View.php(77): OC\AppFramework\Utility\SimpleContainer->get()
#13 /var/www/html/lib/private/Server.php(423): OC\Files\View->__construct()
#14 /var/www/html/lib/private/AppFramework/Utility/SimpleContainer.php(169): OC\Server->OC\{closure}()
#15 /var/www/html/3rdparty/pimple/pimple/src/Pimple/Container.php(122): OC\AppFramework\Utility\SimpleContainer->OC\AppFramework\Utility\{closure}()
#16 /var/www/html/lib/private/AppFramework/Utility/SimpleContainer.php(136): Pimple\Container->offsetGet()
#17 /var/www/html/lib/private/ServerContainer.php(154): OC\AppFramework\Utility\SimpleContainer->query()
#18 /var/www/html/lib/private/AppFramework/Utility/SimpleContainer.php(45): OC\ServerContainer->query()
#19 /var/www/html/lib/private/Server.php(1277): OC\AppFramework\Utility\SimpleContainer->get()
#20 /var/www/html/lib/base.php(635): OC\Server->boot()
#21 /var/www/html/lib/base.php(1224): OC::init()
#22 /var/www/html/console.php(31): require_once('...')
#23 /var/www/html/occ(33): require_once('...')

For information on how to fix the above error please see: OCP\Exceptions\AppConfigTypeConflictException: Config value bruteforcesettings/enabled is stored as boolean but was requested as string