typo3 7.6.4 RTE: Oops, an error occurred!

No image handlers are configured. Check page TSconfig
RTE.default.buttons.image.options.imageHandler.

try this one

RTE.default.showButtons := addToList(image)
RTE.default.proc.allowTagsOutside := addToList(img)
RTE.default.FE.showButtons < RTE.default.showButtons
RTE.default.FE.proc.allowTagsOutside < RTE.default.proc.allowTagsOutside
RTE.default.FE.proc.entryHTMLparser_db.tags.img >

RTE.default.buttons.image.options.imageHandler {
    image {
        handler = TYPO3\CMS\Rtehtmlarea\ImageHandler\EditImageHandler
        label = LLL:EXT:rtehtmlarea/Resources/Private/Language/locallang_selectimagecontroller.xlf:currentImage
    }
    magic {
        handler = TYPO3\CMS\Rtehtmlarea\ImageHandler\AddImageHandler
        label = LLL:EXT:rtehtmlarea/Resources/Private/Language/locallang_selectimagecontroller.xlf:magicImage
        displayAfter = image
        scanAfter = image
    }
    plain {
        handler = TYPO3\CMS\Rtehtmlarea\ImageHandler\AddImageHandler
        label = LLL:EXT:rtehtmlarea/Resources/Private/Language/locallang_selectimagecontroller.xlf:plainImage
        displayAfter = magic
        scanAfter = magic
    }
}