How to Fix Thumbnail Regeneration Failure while Importing WooCommerce Products?

When you import WooCommerce products with images, WordPress dynamically regenerates thumbnails of the images of that product. However, sometimes, even if the full-size images are uploaded, the regeneration of the product thumbnails results in an error, resulting in blank thumbnails.

Image thumbnail regeneration failure can be due to any of the following reasons:

  1. Conflict with any existing image optimizer plugin
  2. ImageMagick and limitations in hosting
  3. Dimensions or size of the image

Conflict with any existing image optimizer plugin

The regeneration of thumbnails while importing can result in an error due to conflict with any existing image optimizer plugin.

When importing an image, if any image optimizer plugin is active, the plugin may try to compress and optimize the images and reduce their size. This prevents the regeneration of thumbnails.

If you are using any image optimizer plugin, and if the error in thumbnail regeneration is due to this conflict, it can be avoided by deactivating the plugin while the import is done and trying the import again.

ImageMagick and Limitation in Hosting

When this is the case, the image regeneration issue can be resolved by adding the line SetEnv MAGICK_THREAD_LIMIT 1  to the top of the .htaccess file.

ImageMagick uses multiple threads to process the images as fast as possible. However, using multiple threads can cause the error of image thumbnail regeneration because of the limitations in hosting that prevent you from running multi-thread tasks.

This can be avoided by limiting ImageMagick to a single thread. The above line sets the number of threads for ImageMagick to 1 and will successfully generate thumbnails for the images.

Dimensions or Size of the Image

If the size or dimensions of the image are too small or too large, WordPress fails to generate thumbnails for that image, or the thumbnails generated will be pixelated or blurry. This can be overcome by making sure that the images being imported are of optimal size and dimensions.

If you are looking for an advanced plugin to import and export WooCommerce products, take a look at our WooCommerce product import export plugin.