JSON response could not be decoded

[Duddy67]

Hi,

Hello,
I installed the PHP Etherpad Lite Client as explained in the Readme.md but when I run the basic php script example I get the following errors:

Fatal error: Uncaught UnexpectedValueException: JSON response could not be decoded in /srv/www/sites/html/myProject/vendor/tomnomnom/etherpad-lite-client/EtherpadLite/Client.php:86 Stack trace: #0 /srv/www/sites/html/myProject/vendor/tomnomnom/etherpad-lite-client/EtherpadLite/Client.php(36): EtherpadLite\Client->call('getRevisionsCou...', 'padID=testPad&a...', 'GET') #1 /srv/www/sites/html/myProject/vendor/tomnomnom/etherpad-lite-client/EtherpadLite/Client.php(334): EtherpadLite\Client->get('getRevisionsCou...', Array) #2 /srv/www/sites/html/myProject/test.php(4): EtherpadLite\Client->getRevisionsCount('testPad') #3 {main} thrown in /srv/www/sites/html/myProject/vendor/tomnomnom/etherpad-lite-client/EtherpadLite/Client.php on line 86

Etherpad Lite runs properly at http://127.0.0.1:9001
Where these errors come from ?
Thanks

Ubuntu 18.04
PHP 7.2.19