Hey there,

It looks like the 'mongo' package has been depreciated with PHP 7. You might have better luck with the following:

pecl install mongodb

For more information you should take a look at the following resources:

https://docs.mongodb.org/ecosystem/drivers/php/
http://stackoverflow.com/questions/34486808/installing-the-php-7-mongodb-client-driver

Regards,
Mike C
Platform Support Specialist
DigitalOcean Support

Hello,

to fix this error at me helps:
sudo apt-get install php-xml php7.0-xml

Enjoy!

i have this problem too
i have php 5.6 and some php 7.1 lib on ubonto 16
so after a lot of search i found that i need to install this list --> and after its works!!

so i installed

apt-get install php-pear

apt-get install pkg-config

apt-get install libbson-1.0

apt-get install libmongoc-1.0-0

apt-get install php-xml php7.0-xml

apt-get install php-dev

then Add the following line to your php.ini file:

extension=mongodb.so

some more information
for php 7.1 you must use the "mongodb" extension
for php 5.6 you need to use "mongo" (dont sure if it must - but i didnt success to use mongodb in php 5.6 )

so for php 5.6 use "apt-get php5.6-mongo"