How to remove the “Source file could not be read” Firefox message? (2024)

Contents

  • What causes the problem?
    • Delete the comprag.dat file
      • Follow these steps:
    • Adjust the “network.http.accept-encoding” setting
    • Make sure the places.sqlite file is not set to Read-only
    • Follow these steps:
      • Alternatively, you can open the folder by following these steps:
    • Open Firefox in Safe Mode
      • These steps will show you how to start Firefox in Safe Mode:
    • Refresh Firefox
    • Clear out temporary files
    • Go through File Explorer:
    • Going through the Settings application:
    • Run the CHKDSK utility
      • Follow these steps to run the CHKDSK utility via File Explorer:
  • Conclusion

How to remove the “Source file could not be read” Firefox message? (1)


Standard web browser problems are mostly network-related. Sometimes, though, you’ll be faced with less common issues, such as the “Source file could not be read” error message in Firefox. While the error occurs in other web browsers as well, it seems to affect Mozilla’s product particularly often.

The message shows up in different scenarios but mainly when you try to download a file. The full error message usually reads as follows:

“FileX could not be saved because the source file could not be read.”

FileX represents the path to the file that you could not save, which will be displayed in the error message.

In this article, we’ll show you how to fix the “Source file could not be read” error when downloading a file via the Firefox browser. The solutions in this article have worked for many users.

What causes the problem?

Finding out how to remove the ‘File could not be saved because the source file could not be read’ error message from Firefox for Windows 10 involves knowing the underlying cause of the problem.

Your internet connection is always the prime suspect, and yes, many users found that they weren’t correctly hooked up. Other, less likely causes are as follows:

  • A problematic compreg.dat file
  • A misconfigured network.http.accept-encoding setting
  • Faulty browser extensions
  • A broken Places.sqlite file

Now it’s time to resolve the underlying causes of the error message.

Delete the comprag.dat file

The comprag.dat file is related to many Mozilla Firefox processes. It’s automatically created whenever you download or install any Firefox product, such as Thunderbird. If the file becomes corrupt, it will cause different kinds of problems, the “File could not be saved” error being one of them.

You’ll have to delete the file to resolve the problem. Once the file is deleted, a new one will be created.

Follow these steps:

  1. Launch Mozilla Firefox.
  2. Once the browser comes up, go to the address bar, type “about:support,” and hit the Enter button.
  3. Once the Troubleshooting Information page shows up, go to Application Basics and click on Open Folder beside Profile Folder.
  4. Once the folder opens, search for the “compreg.dat” file and delete it.
  5. Restart the browser and try downloading the file.

Adjust the “network.http.accept-encoding” setting

The network.http.accept-encoding setting helps tell a server what encoding an HTTP client supports. The setting could be the cause of the error message if it’s misconfigured. Follow these steps to adjust it and see if that will resolve the problem:

  1. Open Mozilla Firefox.
  2. Go to the address bar, type “about:config,” and then hit the Enter key.
  3. Once the “Proceed with caution” warning message appears, click on the “Accept risk and continue” button.
  4. Now go to the search box and type “enco.”
  5. Navigate to the “network.http.accept-encoding” setting and double-click it.
  6. Now delete everything in the box and restart the browser.
  7. You can now check if the error persists.

Make sure the places.sqlite file is not set to Read-only

The places.sqlite file is where Firefox saves your bookmarks and keeps a record of your downloaded files. The download error could be showing up because the file is set to Read-only and the browser can’t write new information to it. Turning off the Read-only function will get rid of the problem.

Follow these steps:

  1. Open a File Explorer window by right-clicking the Start button and selecting File Explorer or pressing the Windows and E keys together.
  2. After the File Explorer window opens, navigate to C:\Users\your_user_name\AppData\Roaming\Mozilla\Firefox\Profiles.

C represents your Windows volume, and “your_user_name” is your current user account’s folder.

Alternatively, you can open the folder by following these steps:

  • Launch Mozilla Firefox.
  • Once the browser comes up, go to the address bar, type “about:support” and hit the Enter button.
  • Once the Troubleshooting Information page shows up, go to Application Basics and click on Open Folder beside Profile Folder.
  1. Once the folder opens, search for the “Places.sqlite” file.
  2. After you find the file, right-click it and select Properties from the context menu.
  3. Once the Properties dialog window opens, confirm that the Read-Only checkbox isn’t marked.
  4. If the box is marked, untick it and click on the OK button.

Open Firefox in Safe Mode

Problematic browser add-ons can disrupt a lot of things, including the download process. So, you have to confirm that this is not an add-on issue. Fortunately, performing this troubleshooting process is easy in Firefox. By starting the browser in Safe Mode, you’re disabling every add-on you installed. If the error message doesn’t show up in Safe Mode, then an add-on is the problem.

These steps will show you how to start Firefox in Safe Mode:

  1. Open Firefox.
  2. Go to the browser’s address bar and type “about:support.”
  3. Hit the Enter key.
  4. Go to the top-right corner of the Troubleshooting Information page and click on Restart with Add-ons Disabled under Try Safe Mode.
  5. The browser will now restart.
  6. Now download the file again and check if the error shows up.

Refresh Firefox

If nothing works, go to the “About:support” page and click on the Refresh Firefox button under “Give Firefox a tune-up.”

Clear out temporary files

Almost every Windows application creates temporary files that become useless over time. These files can become corrupt and start causing different problems. Try clearing them out and see if the download error will disappear for good. There are various ways to remove temporary files, and we’ll be walking you through each.

Go through File Explorer:

  1. Launch a File Explorer window by right-clicking the Start button and selecting File Explorer or pressing the Windows and E keys together.
  2. Once you see the File Explorer window, navigate to the left side and click on This PC.
  3. Go to the right pane and right-click on your Windows volume, which should be Drive C.
  4. Click on Properties in the context menu.
  5. After the Properties dialog window for the drive appears, click on Disk Cleanup.
  6. After the Disk Cleanup utility scans your temporary files, select the types of files you want to delete and click on OK. Click “Clean up system files” if you’re going to get rid of system files that are no longer in use.
  7. After that, restart Firefox and check for the problem.

Going through the Settings application:

  1. Right-click the Windows logo and select Settings from the Power User menu or tap the Windows and I keyboard buttons together.
  2. Once Settings opens, click on the System icon.
  3. After you see the System interface, navigate to the Storage pane.
  4. Under your Local Disk, click on Temporary Files.
  5. After the Temporary Files window shows up, select the file categories you want to clear out, and then click on Remove Files.

Run the CHKDSK utility

Firefox might be unable to download the file because one or more sectors on your hard disk are faulty. Run the CHKDSK utility to fix that problem, then check if the file can download afterward.

Follow these steps to run the CHKDSK utility via File Explorer:

  1. Right-click the Windows logo in your taskbar and click on File Explorer once the Power User menu shows up.
  2. After the File Explorer window appears, go to the left side and click on This PC.
  3. Navigate to the right side of the window and right-click on your Windows volume.
  4. After the context menu drops down, click on Properties.
  5. Once the Properties window appears, switch to the Tools tab.
  6. Next, click on the Check button under Error Checking.
  7. Click on Scan Drive if you see the “You don’t need to scan this drive” dialog.
  8. The CHKDSK utility will now begin to scan your drive.
  9. Once the scan is complete, a dialog will appear and show you the results.

You can run a more thorough scan in the elevated Command Prompt environment. These steps will walk you through the process:

  1. Summon Run by right-clicking the Start button and clicking on Run in the Power User menu. Tapping the Windows and R keys simultaneously will also launch the dialog box.
  2. Once Run opens, type “CMD” into the text field, and then press Ctrl + Shift + Esc.
  3. Once the User Account Control dialog requests permission to run Command Prompt as an administrator, click on Yes.
  4. Immediately the Command Prompt window appears, type in the command below and hit the Enter key:

chkdsk C: /f /r /x

Note that the letter “C” in the command is a placeholder for your Windows volume drive letter.

The additional command switches do the following:

The “/f” switch prompts the tool to fix any error that it finds during the scan.

The “/r” switch prompts the tool to look for bad sectors and recover any readable information.

The “/x” switch prompts the tool to unmount the volume before it is scanned.

If the message below shows up, then the volume you are trying to scan is currently busy. Tap the Y key if the Command Prompt asks you to schedule the scan for your next reboot:

“Chkdsk cannot run because the volume is in use by another process. Would you like to schedule this volume to be checked the next time the system restarts? (Y/N)”

After pressing Y, reboot your PC to complete the check, then try carrying out your backup and check for the error.

Conclusion

The “Source file could not be read” issue is relatively simple to resolve. It will also help to make sure your system is adequately protected against malicious programs capable of attacking your drive. Using a competent anti-malware program that can work alongside Windows Security is a great idea.

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How to remove the “Source file could not be read” Firefox message? (2024)

FAQs

How to remove the “Source file could not be read” Firefox message? ›

1 Answer. Open about:preferences -> Applications. On Extensible Markup Language (xml) action, select "Save File".

How do I fix the Firefox source file could not be read? ›

“The file could not be saved, because the source file could not be read.”
  1. Fix 1 – Find and Delete the Corrupted Compreg.dat file.
  2. Fix 2 – Try Turning off the Browser Extensions in Firefox.
  3. Fix 3 – Check the Attribute Setting for Places.sqlite.
  4. Fix 4 – Reset/Refresh the Firefox browser.
  5. Fix 5 – Reinstall the Browser.
May 17, 2022

How do I fix Pr_end_of_file_error in Firefox? ›

How To Fix the PR_END_OF_FILE_ERROR?
  1. Disable Your Third-Party Security Software.
  2. Disable Your VPN or Proxy.
  3. Reset Firefox's Secure Sockets Layer (SSL) Settings.
  4. Disable the Domain Name System (DNS) Over HTTPS Within Firefox.
  5. Create a New Firefox Profile.
Mar 20, 2023

How do I download XML instead of opening in Firefox? ›

1 Answer. Open about:preferences -> Applications. On Extensible Markup Language (xml) action, select "Save File".

Why am I getting an access denied message in Firefox? ›

The "Access Denied" message with a Reference# is characteristic of a perimeter security system/Web Application Firewall designed to prevent bot and other suspicious connections to the website. Some possible issues to consider: (A) If you are using a VPN when accessing these sites, try without the VPN.

Why Firefox is not open source? ›

Mozilla Firefox is free and open source software, built by a community of thousands from all over the world. There are a few things you should know: Firefox is made available to you under the terms of the Mozilla Public License. This means you may use, copy and distribute Firefox to others.

Why is Firefox blocking everything? ›

You are probably using an extension or a plugin which blocks certain content such as images & videos or advertisements. It may also be possible that your plugin is not updated and therefore firefox shows a red mark and asks you again, if its safe to play.

Why is Firefox blocking download? ›

Firefox includes a download protection feature to protect you from malicious or potentially harmful file downloads. If Firefox has blocked an unsafe download, you will see a warning message about the file in the Downloads panel, along with options for handling the pending download.

Why is Firefox blocking content? ›

Content is blocked based on the domain from which it is to be loaded. Firefox ships with a list of sites which have been identified as engaging in cross-site tracking of users. When tracking protection is enabled, Firefox blocks content from sites in the list.

How to bypass Firefox firewall? ›

On the left side of the Windows Firewall panel, click Allow a program or feature through Windows Firewall. The Windows Firewall Settings window will appear. Find Mozilla Firefox (or firefox.exe) in the list of programs. If it is there, click to select it.

How do I fix corrupted Firefox? ›

  1. Restart your computer. Sometimes problems can be fixed by simply restarting your computer and then starting Firefox again.
  2. Clear your cookies and cache. ...
  3. Restart Firefox in Troubleshoot Mode. ...
  4. Reinstall Firefox. ...
  5. Refresh Firefox. ...
  6. Create a new Firefox profile.

How do I reset my proxy settings in Firefox? ›

To disable the proxy settings on Mozilla Firefox:
  1. Double-click the Mozilla Firefox icon.
  2. In the Mozilla Firefox window, click on Tools then click Options.
  3. Click Advanced.
  4. Click on the Network tab, then click on the Settings button.
  5. In the Connection Settings window, ensure that the No Proxy option is selected.
May 17, 2023

How do I set Firefox to open PDF files not download? ›

To do this, follow these steps:
  1. In the Tools menu, select Options.
  2. In the Options dialog, go into the Applications tab.
  3. Search for and select Portable Document Format (PDF) in the Content Type list.
  4. In the Action list, click on the drop-down arrow. Here you can specify how you want Firefox to handle PDF files.

How do I open a source file in Firefox? ›

View Source lets you look at the HTML or XML source for the page you're viewing. To activate View Source: context-click in the page and select View Page Source. press Ctrl + U on Windows and Linux, or Cmd + U on macOS.

Why can't I read from source file or disk? ›

When transferring files between two different drives (for example, when you transfer files from PC to external hard drive), the most common reason for the "cannot read from the source file or disk" error is mismatched file systems. The most common file systems used in Windows are NTFS and FAT32.

How do I enable source maps in Firefox? ›

Firefox. Open the Developer Tools. Click the Settings cog icon in the upper-left corner of the Developer Tools window. Under the Style Editor section, check the box for Show original sources.

Why wont my PDF open in Firefox? ›

Chosen solution

Go to setting (3 bars) > options > applications. Under applications panel. Find Portable Document Format (PDF) in the list and click on it to select it. Click on the drop-down arrow in the Action column for the above entry and select Use PDF reader name (in Firefox) or preview in firefox.

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