The pdf-to-png tool zips whatever images exist, unless there are none, once its job-tracking JSON file exists, without checking that every expected page was rendered.
Add the suspect PDF file to the upload area to test it.
Adobe's support community documents users encountering an error when exporting a PDF to PNG, which several threads traced back to a damaged or oversized source PDF. Adobe error when converting PDF to PNG - Adobe Support Community - 13021989
PDF To PNGPDF To PNG Not Working
The pdf-to-png tool marks a job failed when the Ghostscript command throws or writes no images at all.
Review the downloaded ZIP file for missing pages.
Checking Incomplete ZIP Downloads
Count the images inside the downloaded ZIP.
Compare the image count against the original PDF page count.
Continue with Fixing Transparency Issues or Improving Text Clarity.
Frequently Asked Questions about PDF to PNG Not Working: Troubleshooting
How do I check if the ZIP is complete?
Open every image file inside the ZIP to check it renders.
Where do I find the converted images?
Extract the downloaded ZIP file to a local folder.
How do I verify the page count?
Scroll through the source PDF and note its total page count first.
What should I do if pages are missing?
Upload the PDF file again to restart the conversion.