Illustrator generated an error message saying it could not save file as PDF

[mvheim]

I had a relatively simply Illustrator artwork for a large scale poster. It contained a few vector objects, no type fonts, but a large bitmap texture background (over 500MB uncompressed RGB). I wanted to save it as a PDF for my print provider.

The first attempt at saving it as PDF used the compression setting "JPEG, Medium" — the resulting PDF file was not compressed whatsoever — the file size was exactly the same as the saved AI format file (587.2MB). So then I tried the setting "JPEG 200 (Automatic), Medium" — this attempt failed after several minutes of churning, and generated an error message suggesting I create a File Package Report and send it to Illustrator support.

System Info:
Mac Studio 2023 M2 Max, 32GB RAM, Sonoma 14.7, 2TB SSD with 1.43GB available
Illustrator 29.1

The file is obviously too large to attach, but I have attached the report below.

[mvheim]

Here is a screenshot of the error message:

[mvheim]

I find it somewhat disturbing that the text of this error message is not properly formatted and does not follow proper English grammar. That seems to imply a certain sloppiness in programming.

[mvheim]

I am continuing to try different settings. I find that it will save successfully as PDF if I use the compression setting "JPEG, Medium", but that it does not actually compress the file size at all. This is a bug, since I have always been able to save files with embedded images at various levels of JPEG compression, and the file size has always reflected the amount of compression. But in this case we are achieving zero compression. What is going on?

[Monika Gause]

Which other options do you set when saving the file?

[mvheim]

My reply seems to have disappeared, so I will repost it:

These screenshots show the settings I used last. With these settings, the final PDF file is 586.2MB. The saved original AI format file was 587.2MB — that shows essentially zero compression (I attribute the saving of 1 MB to the fact that I had "Preserve Illustrator Editing" turned off). For comparison, the placed bitmap image in the file was only 43.2 MB as saved from Photoshop with JPEG compression.

[mvheim]

Success! I changed the following aspects of the document:

1. I converted the document to RGB color (the image was already RGB).

2. I cropped the background image so that it did not extend beyond the artboard (it had a small bleed previously).

3. I deleted a trim guide layer which was set Do Not Print (I often include this in files for outside print producers).

Result: PDF file size became 25.2MB rather than 468.2MB. One of these settings somehow prevented Illustrator from compressing the image file. Is any of these a known bug?

[mvheim]

What????

I just repeated the previous steps on a different copy of the document, which had a slightly larger artboard because it was sized for a different location, and the compression failed again — the "compressed" PDF is exactly the same size as the uncompressed file. This is starting to look like a real wild bug.

[mvheim]

I just repeated the above process. Same result. So was the "succesful" result just a fluke? This makes no sense.

[Monika Gause]

That "Bitmap texture background" - can we please see that?

Is that a Bitmap in the sense of a 1 bit image?

In that case you didn't apply a lot of compression (ZIP doeesn't do a lot in this case).

[mvheim]

No, I said it was a 587MB RGB file.... it is 8-bit. I can't even conceive of the number of pixels that would be required to make a 1-bit file 587MB in size.... yikes.

If you read all my posts, you will see that Illustrator did manage to properly compress the PDF — once. I don't understand why this is not repeatable. I have been very careful to note the settings. I need to do it on the version with the alternate cropping.

[Monika Gause]

Is it still version 29.1 or did it update since? There was a minor update to 29.2 during the last couple of days.

[mvheim]

29.1 is the current version.

[Ton Frederiks]

Is your document a Large Canvas File.

It is hard to tell after it is created, but if you zoom out as much as you can does it look something like this?

[mvheim]

I am afraid I do not know what you mean.

The document artboard was 148 x 16 inches.

[Ton Frederiks]

Large Canvas documents were introduced to enable full scale large sized documents, but that does not mean they cannot contain small artboards (like in my screendump). Unfortunately these Large Canvas documents behave sometimes unexpectedly with regards to compression. That what I was trying to find out. Creating a new document at the correct size and copy paste the contents in that new document is the only way to convert a Large Canvas document to a regular size canvas document.

This is how a zoomed out, normal canvas 148 x 16 inches artboard would look like.

[mvheim]

OK, thanks for the explanation. But I had never heard of "large canvas documents" so I know I did not set it up as one.

[Monika Gause]

The large document might happen without even noticing. WHich size did you set up?

[mvheim]

As I said, the artboard was 148 x 16 inches. I don't even know where the "large canvas document" setting is located. I don't think this line of investigation is relevant — see my latest post.

[mvheim · Accepted solution]

Success! (again). I finally managed to save teh larger crop version of this art. What I did was break the large background art into 2 pieces in Photoshop and place them as separate images (with some overlap). After I did this, I could save a compressed PDF of 31.8 MB from an original Illustrator file of 592MB.

So what I think I have discovered is that Illustrator is incapable of JPEG compression on placed images larger than 500MB. I am surprised that this limitation is not documented.

[Ton Frederiks]

Good to hear you've got it working, but I still wonder if it would have worked if you create a new 148 x 16 inches document and paste the content from your problem document in it.

[mvheim]

You want me to cut & paste a 580MB object? Why won't you believe me when I say I did NOT create a Large Canvas Document? Maybe to start with you could explain how I could have done that inadvertently?

[Ton Frederiks]

It's ok, it was just a question.

You can create a large canvas document by creating a new document with an artboard or multiple artboards that do not fit in a regular canvas. If you create 2 artboards of your 148 x 16 inches you already have a large canvas document. If you click OK and correct the artboard size afterwards it still is a large canvas document.

New documents have the size of the last document, it is easily overlooked that it is a large canvas document and when corrected it is still a large canvas document.

[Ton Frederiks]

Another thing that is easier to do than to cut & paste a 580MB object is to zoom out as far as you can on your problem document, make a screendump and compare it to the first screendump I made of an Large Canvas Document with an artboard of 148 x 16 inches. If it looks like that, you have a Large Canvas Document, if it does look more like my second screendump, it is a regular size canvas.