UBB.threads is not, at this time, capable of running on PHP7 (we actually recommend PHP5.6 currently). We also require the MBString library to be installed, please contact your webhost.

As Isaac previously linked, there was already a discussion on this issue here.

The UBB.threads System Requirements Test will provide any information about your hosting environment which may have issues.

I am a Web Development Contractor, I do not work for UBBCentral. I have provided free User to User Support since the beginning of these support forums.
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