Problem with installing LibreNMS

Hi there, I am a fresh member of the LibreNMS Cmmunity. The reason is that i have problems with the installation of LibreNMS obviously. When i do an ./validate.php i get the following output (this is a partially output):

Fatal Error: Uncaught Error: Call to undefined function LibreNMS\Util\app() in opt/librenms/LibreNMS/Util/Laravel.php:71
Stack trace:
#0 /opt/librenms/LibreNMS/Util/Util/Laravel.php(38): LibreNMS\Util\Laravel::isBooted()
#1 /opt/librenms/includes/init.php(96): LibreNMS\Util\Laravel::bootCli()
#2 /opt/librenms/validate.php(134): require(’/opt/librenms/i…’)
#3 (main)
trown in /opt/librenms/LibreNMS/Util/Laravel.php on line 71

I am struggling with this problem since a few days, and i did not find a solution yet.
Does anyone has a clue?

Greetings, Jos

Not enough information here, but try this:

composer dump-autoload
composer install --no-scripts

and then

composer update

I am aware of the fact that i did not give much information. But what information do you need more? I am a newbee. But i did what you proposed and i got the following output:

Composer could not find a composer.json file in /home/librenms.To initialize a project, please create a composer.json as discribed in the “Getting Started” section.

Let us know what OS are you using at first. The command I gave you you need to run in the directory where you cloned the LibreNMS, not in your home directory.

Ubuntu 18.04.3 LTS codename Bionic

Are you sure that you installed dependencies?

./scripts/composer_wrapper.php install --no-dev

Yes, i just did. There were a few yellow lines passing my screen, i cannot see what it says. The last line says "You can also run ‘php --ini’ inside terminal to see wich files are used by PHP in CLI mode.

Maybe some problems occured during that step. I’d repeat whole process from scratch to be absolutely sure that no errors appeared while it was proceeding.

@Jos_Janssen you have not gotten the PHP dependencies installed.

Can you pastebin the full output of
./scripts/composer_wrapper.php install --no-dev ?