That's absolutely astonishing. I'm still unable to reproduce the issue, and thus have no ideas about any possible solution...
Correct me if I'm wrong. To reproduce the issue one should:
1. Setup standard LAMP system (let it be Debian 8 with Apache 2.4.10, PHP 5.6.30, and multiple modules and PHP extensions as was described
here).
2. Download our official distribution:
https://mibew.org/download23. Unpack the distribution at
/<server document root>/mibew/4. Prepare valid configuration for Mibew Messenger (i.e.
configs/config.yml)
5. Visit
http://<server>/mibew/installRight? Is it a
full list of steps to reproduce the issue
without any missed parts?