Fatal error: Call to undefined function mb_strtolower() on cPanel server

I was facing following error on your site :
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Fatal error: Call to undefined function mb_strtolower() in

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Cause :
The error was due to mbstring php module  was not installed.

Solution:
To resolve this issue need to recompile apache with Multibye string(mbstring) module.
Once apache is compiled your error should be gone.