Certain will generate the error "XML request error: OK (200)" when trying to upload image files using the HTML editor (under Custom HTML, Email Template, Custom block, or anywhere in the application that launches the HTML editor) where the name of the image file contains special characters.
To fix this issue:
- First, ensure that you have the same file name saved on your computer.
- Navigate to Plan > Configure > Display > Advanced.
- On Step 2, select "Overwrite existing file".
- On Step 3, select click "Upload Image/File". After the window refreshes, the "Upload Image/File" button will be renamed to "Delete Image/File".
- Check the box next to "Delete this image/file", then click "Delete Image/File". (see Screenshot below)