Could you please confirm whether you have performed an equivalent test on your side. Specifically, creating a template that includes WebP images, exporting it, and then importing it into another site.
To clarify the behaviour I am observing:
- When the WebP images are replaced with PNG files, the template imports and functions correctly.
- File permissions do not appear to be the cause. I have verified this locally, including the use of custom temporary folders and files, together with a full review of permissions.
- PHP EXIF and
allow_url_fopen are both enabled.
I have repeated this process across multiple environments, including a local Ubuntu server, standard shared hosting, LiteSpeed-based hosting, and several other hosting setups with different providers. The outcome is consistent.
On the local server, there are no security layers such as mod_security, and the site itself is a clean installation with only Pro and UpdraftPlus installed. No additional plugins or themes are present.
While I appreciate the reference provided, pointing to a forum discussion from nearly five years ago is not especially reassuring. A defect of that age would reasonably be expected to have been addressed. Furthermore, if the underlying cause were permissions or configuration, one would expect similar failures across all image formats rather than WebP alone.
PNG and JPEG images import without issue. This strongly indicates that permissions, extensions, and general server configuration are unlikely to be the root cause. The failure occurs only when WebP images are involved. If you can confirm that you have reproduced and tested this scenario independently, I will gladly continue investigating. However, given the range of servers and configurations already tested, the issue appears more closely related to the import process itself.
For completeness, the WebP images were generated in Photoshop and validated directly via SSH:
Command:
file banner.webp
Result:
RIFF (little-endian) data, Web/P image
Additionally, both GD and Imagick are installed with WebP support enabled.
As a further precaution, I explicitly allowed the MIME type within the child theme:
add_filter(‘upload_mimes’, function ($mimes) {
$mimes[‘webp’] = ‘image/webp’;
return $mimes;
});