PHP Fatal error: Call to undefined function mb_strtolower() in upgrade-helper.p

[TomasM]

Hi, I was trying to upgrade from 2.1 beta 2 and every time I get blank page on Step 3 (backup).

Error log shows error (in subject line).

I was playing with changing PHP versions in cPanel: 5.5, 5.6, 7.0, 7.1 but it didn't give any good results.

I also got latest SMF version from Github, but that also didn't resolve the error.

Server info:

cPanel Version    64.0 (build 29)
Apache Version    2.4.25
PHP Version    5.6.30
MySQL Version    5.5.55-cll

Thank you!

[vbgamer45]

Make sure you have the mbstring extension installed in php http://php.net/manual/en/book.mbstring.php

[TomasM]

Thank you! That resolved the problem.