Possible causes and help:
The files of the TSI were manually transferred via FTP not in binary mode to the web space.
Optimally, you should first download the zip archive to the web space and then unzip it there. If files are transferred individually, please make sure that this is done exclusively in the binary procedure, otherwise the above mentioned. Error can occur.
The PHP extension of the IonCube Loader is not installed or not installed correctly.
For installation questions, please contact your hosting provider or contact IonCube directly at the following link: http://www.ioncube.com/loaders.php. Please note that you also need your own IonCube loader for each PHP version, eg. For example, for PHP 7.1 a suitable IonCube Loader for PHP 7.1, for PHP 7.2 a suitable IonCube Loader for PHP 7.2, etc. The error may therefore occur if you have updated the PHP version without setting up a suitable loader.