System configuration check: Error: RecursiveDirectoryIterator::__construct(/var/www/html/mariadb/mysql): Failed to open directory: Permission denied

Hi gu
I installed nextcloud (version 24via Docker-Compose and a mariadb (latest). When I make now check of system configuration I got one error message:

Technical information

The following list covers which files have failed the integrity check. Please read
the previous linked documentation to learn more about the errors and how to fix
them.

Results

  • core
    • EXCEPTION
      • UnexpectedValueException
      • RecursiveDirectoryIterator::__construct(/var/www/html/mariadb/mysql): Failed to open directory: Permission denied

Raw output

Array
(
[core] => Array
(
[EXCEPTION] => Array
(
[class] => UnexpectedValueException
[message] => RecursiveDirectoryIterator::__construct(/var/www/html/mariadb/mysql): Failed to open directory: Permission denied
)

    )

)

When I take a look in the running nextcloud container via “docker exec CONTAINERID bash” and there in the current grants for the directory …/var/www/html/mariadb and its subobjects (directories and files) user and group is both 999 (999:999).

Can you give me any information how I can resolve this issue.

Greetings