Fix Source file could not be read Error on Firefox Browser

Whenever you are browsing the internet, you may come across some file that looks interesting and you may try to download it over to your PC. Many users have reported an error whenever they try to download a file over the internet and save them in a location using the Mozilla Firefox browser. This error can be seen with any type of file that you try to download like audio, video, games, documents, and so on. So, instead of starting the download, an error message is displayed to the user as below.

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

This error message indicates the path of the file that was being downloaded. One of the main reasons for this error to occur is a missing internet connection. So, the first thing that needs to be checked when you receive this error is whether you are connected to the internet and able to browse other web pages.

If you are facing this download error with Firefox and have a working internet connection, then try the fixes mentioned in the article to resolve this Firefox error.


Fix 1 – Find and Delete the Corrupted Compreg.dat file


It has been noticed that the corruption of the Compreg.dat file can lead to this “Source file could not be read error”. Deleting this file has helped many users fix this issue on their Firefox browser.


1. Open the Firefox browser on your PC.

In the address bar, type about:support and hit Enter to open the Troubleshooting Information page.


Firefox About Support Min


2. Once this page opens up, find either the Open Folder or Show Folder button associated with Profile Folder to open the Firefox profiles folder on your PC.


Firefox Troubleshooting Info Select Open Folder Firefox Profiles Min


After the folder opens, close the browser.

3. Go back to the Firefox profiles folder.

Locate the Compreg.dat file.

Select the file and click on the Delete (bin) icon at the top of the File Explorer.


Delete Compreg.dat File Min


4. Launch Firefox again and try downloading the file to check if the issue is resolved.


Fix 2 – Try Turning off the Browser Extensions in Firefox


1. Launch Firefox.

Type about:addons in the address bar and hit Enter to open the Add-ons Manager.

2. Once you are on the Add-ons Manager page, select Extensions in the left panel.

On the right side, all the extensions that you have added to Firefox will be visible.

3. Now, turn off the toggle next to the extensions on your browser to disable them.


Firefox Add On Manager Disable Extension Min


If you want to remove the extension, then click on the three horizontal dot menu associated with the extension and choose the Remove option.


Firefox Add On Manager Remove Extension Min


On the confirmation prompt, click on the Remove button once again.


Firefox Add On Manager Remove Extension Confirm Min


4. Check if the error while downloading a file in Firefox is fixed.


Fix 3 – Check the Attribute Setting for Places.sqlite



1. Open the Firefox browser.

To go to the support page in Firefox, type about:support in the address bar and hit the Enter key.


Firefox About Support Min


2. On this page, locate the Open Folder button.


Firefox Troubleshooting Info Select Open Folder Firefox Profiles Min


Click on Open Folder to open the Firefox profiles folder in your systems file explorer.

3. In the profiles folder of Firefox, find the file named places.sqlite within it.

Right-click on this file and then choose Properties in the menu that opens.


Firefox Profiles Places.sqlite Properties Min


4. In the Properties window for the places.sqlite file, select the General tab.

Here, make sure that the box next to Read-only is unchecked in the Attributes section.

Click on Apply and then on OK to save these changes.


Firefox Profiles Places.sqlite Properties Uncheck Readonly Attribute Min


5. Check if this resolved the Source file could not be read error.


Fix 4 – Reset/Refresh the Firefox browser


1. Open Firefox and go to the troubleshooting page by typing in about:support in the address bar.


Firefox About Support Min


2. On the Troubleshooting information page, click on the Refresh Firefox… button at the right end below Give Firefox a tune-up.


Firefox Troubleshooting Info Refresh Firefox Min


3. Click on the Refresh Firefox button again in the dialog window that indicates refreshing will reset the browser to its default settings.


Firefox Troubleshooting Info Refresh Firefox Confirmation Min


4. Relaunch the browser and check if the problem is fixed.



Fix 5 – Reinstall the Browser


1. Press Windows + R on your keyboard to open the Run box.

Type ms-settings:appsfeatures and hit Enter to open the Apps & features page.


Run Settings Apps Features Min


2. On this page, scroll down to the App list section and type firefox in the text box below App list.

When you see the search result, click on the three vertical dot menu associated with Mozilla Firefox.

In the menu that opens up, choose the option Uninstall.


Apps Features Firefox Uninstall Min


Click on Uninstall when you are prompted to confirm the app uninstallation.


Apps Features Firefox Uninstall Confirm Min


3. Wait for the uninstallation process to complete. You may need to follow the instructions on the screen to finish the process.

4. Visit the Official Download Page for Firefox.

Here, click on the Download Firefox button to download the app installer.


Download Firefox Installer Min


Open this downloaded file and complete the installation following the on screen instructions.

5. After the installation, launch the browser and check if the file can be downloaded without any errors.



Thanks for reading.


We hope this article has helped you resolve the Source file could not be read error in Firefox on your Windows PC. Did you find this article informative enough in clearing the problem associated with your Firefox browser? Please let us know the fix that worked for you in the comments section below.