File Corruption & Recovery

How to Fix a Microsoft Project File That Suddenly Becomes Extremely Large

Camila Milosovich Oct 16, 2026 869 views

Question details

The user is experiencing a massive, unexpected increase in the file size of a Microsoft Project document, leading to application freezing and sluggish performance.

How to Fix a Microsoft Project File That Suddenly Becomes Extremely Large

Product: Microsoft Project
Device & OS: not provided
Scenario: Modifying dates or continuing work within an existing Microsoft Project file.
Observed behavior: The file size suddenly balloons from a few hundred kilobytes to several gigabytes, which is a strong indicator of file corruption, causing the software to freeze or run very slowly.

Before you start

Before attempting to fix the file, locate your bloated Microsoft Project file and copy it to a safe, separate folder to ensure you have a backup if the recovery process fails.

Solution 1Recommended

Update Microsoft Project and Convert File to XML

This is the most effective and recommended method for stripping out corruption from a bloated Microsoft Project file while retaining your project data.

A sudden jump in file size from kilobytes to gigabytes is a classic symptom of file corruption in Microsoft Project. Converting the corrupted file into an XML format strips away the underlying broken data structures.

Ensure you are running the latest version of Microsoft Project before proceeding, as outdated versions are more prone to processing errors.

Check for updates

Open Microsoft Project, navigate to File > Account, and select 'Update Options' to ensure you are running the newest software version.

Save as XML

Open your bloated project file, go to File > Save As, choose a destination folder, and select 'XML Format (*.xml)' from the 'Save as type' dropdown menu.

Re-import the XML file

Close the current project completely. Go to File > Open and browse to the XML file you just saved. When prompted by the system, choose to open it as a new project.

Save as a standard MPP file

Once the XML data is successfully imported, go to File > Save As and save the new project back to the standard Microsoft Project format (*.mpp). Check the file properties to verify the size has normalized.

Update Microsoft Project and Convert File to XML

Verify File Size: If the corruption was successfully removed, your newly saved .mpp file should be reduced back to a reasonable size (typically under a few megabytes).

Free Microsoft Office alternative

Experience a Lightweight and Reliable Office Suite

While Microsoft Project is strictly for complex project management, bloated files and sluggish performance shouldn't plague your everyday office tasks. For your core documentation, data analysis, and presentations, switch to WPS Office. It provides a lightweight, highly compatible alternative to Microsoft Office that saves local storage and prevents heavy resource usage.

1. Download WPS Office: Visit the official WPS Office website and click the free download button for your operating system.
2. Install the Suite: Run the lightweight installer and follow the simple on-screen instructions to set up the software in minutes.
3. Open Your Office Files: Drag and drop your existing Word, Excel, or PowerPoint files directly into the WPS Office workspace to continue working immediately.

Fully compatible with Microsoft Word, Excel, PowerPoint, and PDF formats.Lightweight installation ensures smooth performance without system freezing.Free to use with a familiar, tabbed user interface for seamless migration.Built-in robust file saving features minimize the risk of document corruption.

microsoft office alternative - wps office

Frequently Asked Questions

Why does my Microsoft Project file suddenly become so large?

Sudden, massive increases in file size are typically caused by file corruption. This often occurs when copying and pasting tasks from external software, experiencing network interruptions during a save, or operating on an outdated version of Microsoft Project.

Can I recover a corrupted Project file without converting it to XML?

Sometimes, copying all the tasks and pasting them into a completely blank, new project file can bypass the corruption. However, the XML conversion method is generally the most thorough way to strip out corrupted background data.

Does updating Microsoft Project prevent future file corruption?

Yes, keeping Microsoft Project updated ensures you have the latest bug fixes and stability improvements. The developers frequently patch known processing issues that lead to file size bloating and system freezing.

Document & File Issues