Upgrading Drupal

After updating Drupal 8 to Drupal 9, the following error is displayed on the website page:

Warning: file_put_contents(): Filename cannot be empty in /var/www/html/web/modules/contrib/devel/src/DevelDumperManager.php on line 108

Although it is not in the logs. But there is a similar one:
 

Apologies if this is post is in the wrong area, but I just had an odd thing happen.

I'm running a multi-site Drupal 9 installation on a CentOS distro, and I just updated the core package and modules to 9.3.12. This installation is currently not accessible outside of my network.

Hi,

I'm trying to upgrade from Drupal 8 to Drupal 9.

According to this, I'm running the following:

I've always ran composer update to upgrade Drupal and packages. After a recent composer upgrade to version 2.2.12, I was prompted with an additional security check asking to allow modification to composer.json which added the following. Can anyone confirm "composer update" is still the correct method of upgrade?

A cautionary tale for others who might end up here:

Our multi-EC2-instance site had been successfully running Drupal 9.3.3, with an initial non-cached page rendering time of ~0.3s.

By way of testing Drupal 9.3.11, we added two EC2 instances running that version, updating modules at the same time, and ran these live against the same database.

The result: page rendering time jumped to ~5s, the site quickly became unavailable, and I ended up with a load average of 50+ and all instances, with 100+ sleeping MySQL connections.

hi :)

Sorry if question is noob but I am not develloper professional.... xD

I have a Drupal site 8 make in 2016, I have follow all steap for convert my site in Composer 8.9 --dev here:

https://www.drupal.org/docs/installing-drupal/add-composer-to-an-existin...

Soo, now, I can use Composer, it is oki, but my version is --dev, soo, it il oki???

Module Drupal 9 upgrade status telle me in yellow :