Upgrading Drupal

Hello,
In the course of trying to upgrade from 8.9.6 to 9.0.6 I ran .../admin/reports/upgrade_status. 
Besides getting a number of errors for deprecated functions, etc., I also get messages about 
putting "core_version_requirement: ^8 || ^9 to designate that the module is compatible with Drupal 9" 
into the respective ...info.yml files. 
After doing so and clearing the caches, I still get the same error message. 
What am I missing?
Regards
H. Stoellinger

Since upgrading from 8.9.6 to 9.0.6, users can only see the front page if they are logged in. The log says:

Path: /. Drupal\Core\Http\Exception\CacheableAccessDeniedHttpException: The 'access content' permission is required. in Drupal\Core\Routing\AccessAwareRouter->checkAccess()

But in the permissions page, there is no Access Content permission. The only "access" is to assess the file overviews page.

Hello,

I have an issue and hope you can help. I want to upload a category description, but after submitting it, it doesn't appear in the category.

Im updating several sites from Drupal 8.8.8 and  Drupal 8.6 (something). Updating to Drupal 8.9.6

and get this error:

Mismatched entity and/or field definitions

The following changes were detected in the entity type and field definitions.

Buen día compañeros,

Tengo un sitio ya en Drupal 8 y el cliente quiere un LMS (e-learning) en este, encontré una distribución que se llama "Opigno LMS", todo funciona muy bien, pero ya tengo nodos, taxonomías y demás en el sitio actual, ¿Cómo me recomiendan hacer el paso de esta información a Opigno?.

De antemano, le doy gracias a quien me pueda dar alguna sugerencia o guía y me disculpo si el tema no va en esta seccion.

Muchas gracias.

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Translation with Google, sorry, my English is not good

Hi,

I moved my intranet (Drupal 7) from a php 5.6 server to a php 7.4. I updated modules that were giving errors and the core to the last 7.x version, but when I try to open the website a general error apperas on the screen, and in the log I can see:

php  Error: Call to undefined function ereg() in eval() (line 2 of /var/www/intranet/modules/php/php.module(80) : eval()'d code).