PDF Editing Issues

How to Fix Not Enough Memory Error When Underlining Text in Acrobat Reader

Phi Hung Vo Oct 19, 2026 869 views

Question details

The user encounters a memory availability error when attempting to underline text in a PDF document stored in Document Cloud using a mobile application.

How to Fix 'Not Enough Memory Available' Error in Acrobat Reader

Product: Adobe Acrobat Reader
Device & OS: Mobile devices
Scenario: Underlining or annotating text in a PDF file hosted on Document Cloud via the mobile app.
Observed behavior: The application displays a 'Not enough memory available' error despite having sufficient local device storage, and the edited file sometimes reverts to an older version.

Before you start

Ensure your mobile device is connected to a stable internet network and close unused background applications to free up active system memory (RAM) before editing cloud documents.

Solution 1Recommended

Test Local Editing and Free Up Cloud Storage

Isolate the issue by testing a locally stored PDF and clearing unnecessary files from your Document Cloud to prevent synchronization conflicts.

Often, memory errors on mobile apps relate to active RAM limits or cloud sync bottlenecks rather than the physical storage space on your device.

Save the PDF locally

Tap the options menu (three dots) in Acrobat Reader and select 'Save a Copy' to save the PDF directly to your device's internal storage.

Edit the local file

Open the newly saved local copy of the PDF and attempt to underline the text. If it works smoothly, the issue lies with cloud synchronization.

Clear Document Cloud space

Navigate to the Document Cloud file browser within the app, select outdated or unnecessary files, and delete them to free up cloud storage capacity.

Sync Warnings: Wait for files to fully upload to Document Cloud before closing the app to prevent your edits from reverting to older versions.

Solution 2

Verify Cross-Platform Functionality

Check if the bug is specific to the current mobile version of Acrobat Reader by testing the exact same file on a desktop computer.

Efficient PDF Editor

Underline and Edit PDFs Seamlessly with WPS Office

Avoid memory errors and cloud sync crashes by using WPS Office. Our lightweight architecture provides powerful, stable PDF editing tools, allowing you to easily underline, highlight, and annotate documents on mobile devices without lag.

1. Install WPS Office: Download and install the free WPS Office app from your device's app store.
2. Open your PDF: Launch WPS Office, navigate to the 'Files' tab, and open your target PDF document.
3. Access Annotation Tools: Tap the 'Edit' or 'Annotate' icon at the bottom of the screen to reveal the markup toolbar.
4. Underline and Save: Select the underline tool, drag across your desired text to highlight it, and tap 'Save' to ensure your edits are securely stored.

Lightweight mobile application with optimal memory managementSeamlessly underline, highlight, and annotate PDF textFully compatible with standard Adobe PDF document formatsStable built-in cloud sync prevents edit reversals

microsoft office alternative - wps office

Frequently Asked Questions

Why does the app say 'not enough memory' when I have plenty of phone storage?

This error typically refers to active system memory (RAM) or limitations within the cloud storage sync process, rather than your device's physical hard drive space. Heavy PDF files or having too many apps open can exhaust available RAM.

Can I recover my PDF edits if the file reverted to an older version?

If a memory crash or sync failure caused the file to revert, un-synced cloud edits are generally lost. It is highly recommended to manually save a local copy before making extensive annotations.

Does underlining text increase the PDF file size significantly?

No, simple text annotations like underlining or highlighting add very minimal data to the file size. However, if the PDF contains complex vector graphics, the app might struggle with memory allocation during the rendering process.

PDF Troubleshooting