After upgrading to Magento 2.2.0 I found the following ioncube.so error when running SSH commands via Composer.
Failed loading /usr/local/ioncube/ioncube.so: /usr/local/ioncube/ioncube.so: undefined symbol:
This was being called in my php.ini
zend_extension = /usr/local/ioncube/ioncube.so
Full Error
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Failed loading /usr/local/ioncube/ioncube.so: /usr/local/ioncube/ioncube.so: undefined symbol: zend_block_interruptions
Loading composer repositories with package information
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It seems that ioncube is not supported by PHP7.1.0.
So the line should be commented out (;) or removed from your global php.ini
;zend_extension = /usr/local/ioncube/ioncube.so
