2 Sep 13, 2016 22:33
Your web host seems to be installing an old version of b2evolution that is not compatible with PHP7. More recent versions of b2evolution are compatible with PHP7 and don't have this bug.
Please replace the b2evolution files on your hosting plan with the latest version that you can download here: http://b2evolution.net/downloads/ . This way it will work with PHP 7.
Basically, you need to follow the manual upgrade procedure described here: http://b2evolution.net/man/upgrade-instructions (you might start at step 3, since you don't have anything precious to backup yet).