Firefox NS_ERROR_NET_PARTIAL_TRANSFER fix for large pages

Quick fix: Clear your cache (30 seconds)

This is the first thing to try. 8 out of 10 times, a partial transfer error is just bad data stuck in Firefox's cache.

1. Click the menu button (three lines) in the top-right corner.
2. Select Settings.
3. On the left, click Privacy & Security.
4. Scroll down to the Cookies and Site Data section.
5. Click Clear Data.
6. Check the box for Cached Web Content only. Leave cookies unchecked if you want to keep logins.
7. Click Clear.

After you do this, reload the page. If it works now, you're done. If not, move to the next step.

Moderate fix: Check proxy settings (5 minutes)

Firefox has its own proxy settings separate from Windows. If they're set wrong, large pages fail because the connection drops mid-transfer.

Here's how to check them:

1. Open Firefox and type about:preferences#general in the address bar. Press Enter.
2. Scroll down to Network Settings.
3. Click the Settings button.
4. Look at what's selected. If it says Use system proxy settings, that's usually fine. But many users see Manual proxy configuration with something like localhost:8080 or a weird IP.
5. If it's set to manual but you don't use a proxy, select No proxy and click OK.
6. If it's already on Use system proxy settings, try switching to No proxy temporarily to see if that fixes it.

After you change this, reload the page. If it loads fine, the proxy was the problem. You can switch back to system settings later if you need a proxy for work or school.

If you're using a corporate or school network that requires a proxy, here's a real-world example: I've seen this error with large PDFs or image-heavy dashboards on Cisco's proxy. The proxy server times out before Firefox gets all the data. In that case, ask your IT team if they can increase the timeout, or try the advanced fix below.

Advanced fix: Reset Firefox network settings (15+ minutes)

If the simple fixes didn't work, something deeper is broken. Maybe an extension changed network settings, or a previous proxy tool left junk behind.

Step 1: Disable all extensions

1. Type about:addons in the address bar.
2. Click Extensions on the left.
3. Disable every extension by toggling each switch to off.
4. Restart Firefox and try the page.

If the page loads, enable extensions one by one until you find the troublemaker. I've seen ad blockers and VPN extensions cause this error a lot.

Step 2: Reset network settings in Firefox

This clears all custom network preferences back to factory defaults.

1. Type about:config in the address bar. Click Accept the Risk and Continue.
2. In the search box, type network.http.
3. Look for preferences that have been modified. They'll be shown in bold. Modified entries often have weird numbers or strange values.
4. Right-click each bold item and select Reset.
5. Pay extra attention to these two:
   • network.http.max-connections – should be 900 by default
   • network.http.max-persistent-connections-per-server – should be 6

After resetting everything, restart Firefox. This has fixed the error for users with misconfigured proxy scripts that set bad limits.

Step 3: Flush DNS cache

Sometimes the issue is outside Firefox, in your computer's DNS cache.

On Windows 10 or 11:

1. Press Windows key + R, type cmd, press Enter.
2. In the Command Prompt, type ipconfig /flushdns and press Enter.
3. You should see: Successfully flushed the DNS Resolver Cache.

On macOS:

1. Open Terminal.
2. Type sudo dscacheutil -flushcache; sudo killall -HUP mDNSResponder and press Enter.

Now restart Firefox and try the page again.

Step 4: Test without any proxy at all

For testing only, turn off all proxy settings in Firefox and Windows.

Windows 10/11:

1. Go to Settings > Network & Internet > Proxy.
2. Turn off Use a proxy server if it's on.
3. Also turn off Automatically detect settings.

This is temporary. If it fixes the error, you know your proxy setup is causing it. You can re-enable settings after testing.

When nothing else works

If you still see the error after all these steps, it might not be Firefox at all. Some websites are just slow or have server issues. Try the same page in Chrome or Edge. If it fails there too, the problem is on the website's end. Wait a few hours and try again.

Also check your internet connection. A weak Wi-Fi signal or a bad Ethernet cable can cause partial transfers. Plug directly into your router if you can, just to test.