Fix charset `utf8mb4_unicode_ci' not supported ?

[SecondSight]

Hello !

I have this error on my boards :

[[Template forums/front/index/forumRow is throwing an error. This theme may be out of date. Run the support tool in the AdminCP to restore the default theme.]]

Running the support tool doesn't fix it.

According to support, the problem  looks to be that mbstring that is on the system at the moment does not support the charset within my database.

html_entity_decode(): charset `utf8mb4_unicode_ci' not supported, assuming utf-8

Does someone know how to fix this, or a way to get rid of this error ?

I use WHM/Centos 7.

Thank you !

[SecondSight]

In the end, I re-installed the server, with Centos 6 and it's doing fine so far.