Optimizing error: An error was encountered while flattening transparent objects

[Warm_Hearts_Publishing]

When I try to save as an optimized PDF, I get the following error message: An error was encountered while flattening transparent objects. I am on a Mac using the current version of Acrobat Pro DC.

[Karla_Design]

I have the same issue right now, and need to get this resolved ASAP. I'm on a PC using the Adobe Cloud. It is with a substantial fillable form created in InDesign, then I export to .pdf and replace the file in the 40-page fillable form with the new .pdf. I don't remember selecting any transparency in the InDesign file. I'm not sure how to isolate the issue. I know it's not in the fillable part of the form. It seems to be in the .pdf. HELP!

[Test Screen Name]

Turn off transparency flattening if you don't need it.

[Warm_Hearts_Publishing]

I have to flatten the images in my PDFs.

[Test Screen Name]

But you said you didn't think you put any transparency in the design? So what is it that you are flattening? What is your aim? I ask because people use "flatten" to mean different things. And it isn't usually images.

[Warm_Hearts_Publishing]

Just to clarify, I DO use graphics with transparency and I am required to flatten them by the clipart artists that I purchased them from. Karla Design is the person who said she didn't think she had used any transparency.

[Test Screen Name]

Sorry for my confusion. If the PDF optimizer is failing in flattening transparency it's worth trying the transparency flattener instead.  May work, or fail with better messages.

[Warm_Hearts_Publishing]

Thanks Test Screen Name. Where do I find the transparency flattener?

[Test Screen Name · Accepted solution]

It's part of the (confusingly named) flattener preview under print production.