Podcast listening platforms require cover art images to be within super specific guidelines. Without it, they can't publish the podcast.
Cover images must be:
1.) a perfect square
2.) between 1400 x 1400px and 3000 x 3000px
3.) have a file size less than 1MB (500kb is optimal)
4.) .jpg or .png file format
5.) RGB colorspace
In this example from Cast Feed Validator, the image is a perfect square (1500 x 1500px) but the file size exceeds that 1MB maximum:
Check out our article on ▶️ How to check the health of your podcast's RSS feed and Apple Podcasts for Creators artwork troubleshooting guide for additional details.
After making adjustments to the image save the file with a slightly different name than the original and upload it again.
To replace the cover image
1. Sign into your Castos dashboard and click Settings to open the Podcast Settings page
2. Select Feed Details
3. Click Choose File:
4. Select the file containing the updated version of the image and click Open
5. Click Save Podcast Details
NOTE: It can take up to 24 hours for Apple Podcasts and other podcast listening platforms to apply the update.
For more information about cover art images, please check out the following resources: