Unable to load dynamic library

Hello,
sporadically I get this error from Codeigniter:
Unable to load dynamic library '/usr/lib/php/20151012/php_openssl.dll'
(also ../php_soap.dll appeared).

There is no php code related to ssl or soap!
This happens always simoultaneously with json error 4 (syntay error?!).

My application runs on ubuntu, so I do not understand why windows dll's are referenced?!

When I logout and login again all functions work properly ,but at subsequent calls of one site
the error appears.

any suggestions?