Error: Declaration of OCA\Theming\ThemingDefaults::getSlogan()

ℹ️ Support
1

The following errors are occurring every 1 second.

[PHP] Error: Declaration of OCA\Theming\ThemingDefaults::getSlogan() should be compatible with OC_Defaults::getSlogan(?string $lang = NULL) at /MY-NEXTCLOUD/apps/theming/lib/ThemingDefaults.php#51

GET /index.php/apps/logreader/poll?lastReqId= ?????????????

It seems to have started happening after the NC administrator logged in for the first time today. I haven’t made any changes to the system, NC app updates, etc.
I disable the Theming app and the error stops. What is the cause of this error?

Nextcloud 18.0.4, php 7.3.17, nginx 1.16.1, MariaDB 10.2.29

2

I have reinstalled Nextcloud18. I’ve re-downloaded Nextcloud.
Then the error seems to have stopped. After all, the cause is not yet known.