package inputenc error unicode char (u + 190) not set up for use with latex

Help, package inputenc error:

unicode char (u+190) not set up for use with latex.

I use \usepackage[utf8]{vietnam}

• Welcome to TeX.SX! Please help us (and also you) and add a minimal working example (MWE), that illustrates your problem. Reproducing the problem and finding out what the issue is will be much easier when we see compilable code, starting with \documentclass and ending with \end{document}. – Bobyandbob Jul 22 '17 at 13:08

The glyph is identical to a Cyrillic character:

\documentclass{article}
\usepackage[X2,T1]{fontenc}
\usepackage[utf8]{vietnam}

\DeclareTextSymbolDefault{\CYREPS}{X2}
\DeclareTextSymbolDefault{\cyreps}{X2}

\DeclareUnicodeCharacter{0190}{\CYREPS}
\DeclareUnicodeCharacter{025B}{\cyreps}

\begin{document}

ABCDEƐF

abcdeɛf

\end{document}