CORS Error Angular

ERROR:
Access to XMLHttpRequest at ‘localhost:8000/version’ from origin ‘http://localhost:4200’ has been blocked by CORS policy: Cross origin requests are only supported for protocol schemes: http, data, chrome, chrome-extension, https.

CODIGO ECHO:
func CORSMiddleware() echo.MiddlewareFunc {

return middleware.CORSWithConfig(middleware.CORSConfig{
	Skipper:          middleware.DefaultSkipper,
	AllowOrigins:     []string{"*"},
	AllowMethods:     []string{"*"},
	AllowHeaders:     []string{"*"},
	AllowCredentials: false,
	ExposeHeaders:    []string{""},
	MaxAge:           0,
})

}

e.Use(middlewares.CORSMiddleware())

CODIGO ANGULAR:

return this.http.get(this._envService.env.url_back + ‘/version’).subscribe(
r => {
this.versionBack = r[‘data’][‘version’];
},
r => {
this.versionBack = ‘error al obtener la version’;
}
)