Fix Unknown Error When Dropping PNG Files into Acrobat Pro DC
Question details
Users encounter an 'Unknown Error' when attempting to drag and drop PNG files into Adobe Acrobat Pro DC to create a multipage PDF.
- Product
- Adobe Acrobat Pro DC
- Device & OS
- macOS Mojave
- Scenario
- Dragging and dropping exported PNG files to generate a multipage PDF document after recently upgrading software.
- Observed behavior
- Acrobat produces an 'UNKNOWN ERROR' message upon dropping the PNG files and completely fails to create the multipage PDF.
Ensure you have a stable internet connection to download software updates, and verify that your PNG files are not corrupted by opening them in a standard image viewer first.
Install the Latest Acrobat DC Optional Update
Applying the latest official patch from Adobe directly resolves the PNG import bug introduced in the 2019 upgrade on macOS.
Adobe has acknowledged a bug occurring after upgrading to Illustrator 2019 and Acrobat 2019 on macOS Mojave. This specific issue prevents PNG files from being recognized correctly during drag-and-drop operations, leading to an unknown error. Installing the official optional update restores full functionality for image imports and multipage PDF creation.
Launch your Adobe Acrobat Pro DC application on your Mac.
Click on the 'Help' option located in the top menu bar of your screen.
Select 'Check for Updates...' from the dropdown menu to prompt the Adobe updater.
Follow the on-screen instructions to download and install the latest optional updates for both Acrobat DC and Reader DC.
Once the installation is complete, restart Adobe Acrobat and try dropping your PNG files into the interface again.
Create Multipage PDFs from PNGs Instantly with WPS Office
Bypass update errors and complex troubleshooting by using WPS Office. The built-in WPS PDF tool offers a lightweight, highly stable environment to quickly combine multiple PNG images into a single, high-quality PDF document.
- 1. Open WPS PDF: Launch WPS Office on your device and click on the 'PDF' tab on the main interface to access the PDF tools.
- 2. Select Picture to PDF: Locate and click the 'Picture to PDF' option found within the quick tools or conversion menu.
- 3. Add PNG Files: Click the 'Add Pictures' button or simply drag and drop your exported PNG files directly into the conversion window.
- 4. Convert to PDF: Arrange your images into the correct page sequence, customize the layout settings if necessary, and click 'Convert' to instantly generate your multipage PDF.
Frequently Asked Questions
Why does Adobe Acrobat show an unknown error when importing PNGs on macOS?
This error is typically caused by a known software bug introduced during the 2019 upgrades of Adobe Acrobat and Illustrator on macOS Mojave. It disrupts the library responsible for parsing PNG imports, which is why an official patch is required to fix it.
Can I combine multiple PNG files into one PDF without using Adobe Acrobat?
Yes. You can use native macOS tools like Preview to select multiple images and print them to PDF, or utilize a reliable third-party suite like WPS Office, which features a dedicated 'Picture to PDF' tool for easy conversion.
Should I convert my PNG images to JPEG to avoid PDF import errors?
While converting PNGs to JPEGs can serve as a temporary workaround if your PDF editor is struggling to process PNG files, modern professional PDF editors natively support PNGs. Applying software updates is the recommended permanent solution.
