Installing couchbase php extension

Hi Im using Ubuntu 18, just installed Couchbase PHP SDK and after adding to php.ini Im getting error

PHP Warning: PHP Startup: Unable to load dynamic library ‘/usr/lib/php/20160303/’ - /usr/lib/php/20160303/ undefined symbol: zend_string_init_interned in Unknown on line 0

anyone have idea whats wrong?

What version of PHP do you use? What version of Couchbase SDK and how did you install it?

PHP 7.1, I did instruction from official website:

sudo dpkg -i couchbase-release-1.0-6-amd64.deb

Will install or upgrade packages

sudo apt-get update
sudo apt-get install libcouchbase-dev build-essential php-dev zlib1g-dev
sudo pecl install couchbase