ruby 2.1
WEBrick 1.3.1

Internal Server Error
(erb):58: syntax error, unexpected end-of-input, expecting keyword_end ; _erbout.force_encoding(__ENCODING__) ^
文法エラー、予期せぬend-of-input、keyword_endを待つ;

_erbout.force_encoding(__ENCODING__) ^
って何でしょうか?