The specified file stats.svg could not be uploaded. The image file is invalid or the image type is not allowed. Allowed types: Only JPEG, PNG and GIF images are allowed.

It seems the issue originated from the update described in Drupal 7.99 → , as detailed in this change record → .

The problem can be resolved by modifying the validation condition to include $file->filemime != 'image/svg+xml', allowing SVG files to bypass the strict image checks that were causing errors.

Thanks for reporting this. I think this is something which needs to be changed in the svg_image module in the svg_image_field_widget_form_alter() function. Currently the module is altering the #upload_validators (see here).

In 🐛 Users are able to upload 0-byte images Fixed a new upload validator was added (see here):

+    $elements[$delta]['#upload_validators']['file_validate_is_image'] = array();

The module can remove the new validator to work as before.

Or you can use hook_field_widget_form_alter to remove it in the custom module as well.