[BUG] Crashes Randomly on Splash Screen | Device-Environment Specific

[kiyokodyele]

Describe the bug When not opened for a long time (1 week+) then open it thereafter, it will just show only the splash screen not the main window. Probably post piracy detection planted? But if you will install a new version or re-extract the same version, it will work. I noticed this starting from version 7.0.0

To Reproduce Steps to reproduce the behavior:

1. Just not use the FE for a long time like (2 weeks maybe?)
2. Then run FE, (will only show splash screen then auto-closes)

Expected behavior FE will run normally

Screenshots Not applicable

Screenrec Not applicable

Device (please complete the following information):

• Type: Desktop
• OS: Windows 11 Pro
• Browser: ?
• Version: 24H2

Additional context I even tried to restart my PC and still doesn't work. Also, same thing happens both my pc and laptop.

[ZhiFenBL]

Not sure, but maybe some software (ex: firewall software) blocking the msojocs server automatically? The msojocs-server should work once allowed through firewall. 🤔

[kiyokodyele]

Not sure, but maybe some software (ex: firewall software) blocking the msojocs server automatically? The msojocs-server should work once allowed through firewall. 🤔

I will try disabling the firewall when it happens again to confirm.

[kiyokodyele]

Not sure, but maybe some software (ex: firewall software) blocking the msojocs server automatically? The msojocs-server should work once allowed through firewall. 🤔

I will try disabling the firewall when it happens again to confirm.

It's not the Firewall. I disabled mine on my laptop while the bug still exists. https://youtu.be/hmhHqGoWLdA

[auto-yui-patch]

Hmm... Several users have reported similar issues on this automaton repo and on msojocs' fiddler-everywhere-enhance. I’ve got no idea what’s going on since I’ve never been able to reproduce the issue, and around 1000 others use it without problems. So, we’ll need to investigate further.

Have you tried:

1. Changing msojocs server port?
2. Checking if this happens when you patch manually too? (If so, you might want to report it on the fiddler-everywhere-enhance repo as well.)
3. Do you suspect anything you did on your system before installing FE 7.0.0?

You should check the logs as well - having them here would be helpful. You’ll likely see the msojocs server startup fail when you start FE from the terminal. You can access the logs in %APPDATA%\Fiddler Everywhere\Logs

[choneas]

I’m experiencing the same issue recently. In my case, the app always crashes. I tried disabling both the network and the public firewall, but that didn’t help. I also deleted the folder in AppData, but the problem persists.

Windows 11, FE 7.4.0

• Here's what happens when I try to run it on terminal: terminal.fe.7.4.0.20251106215225.log

• C:\Users\Choneas\AppData\Roaming\Fiddler Everywhere\logs\electron.log:

  electron.202511062200.log

• Here's more but I did not change them:

  netsh interface ipv4 show excludedportrange protocol=tcp
  
  Protocol tcp Port Exclusion Ranges
  
  Start Port    End Port
  ----------    --------
        8820        8919
        8934        9033
        9129        9228
        9329        9428
        9549        9648
       50000       50059     *
       59100       59100     *
  
  * - Administered port exclusions.
  

[auto-yui-patch]

@choneas Tnx for information.

In your case, the server tries to bind to port 8868, but since that port falls within the restricted range 8820–8919, the binding fails, right?

And, as you can see the error is logged by Fiddler Everywhere app, not msojocs server. So you shouldn't be able to run fiddler everywhere even without patch applied.

Can you please check that? (Running official FE without patch)

[choneas]

Hello, @auto-yui-patch

You're right — I’ve just installed the latest official FE release, and the same issue still occurs.

The electron.log also shows:

Server error log during start: System.IO.IOException: Failed to bind to address http://localhost:8868.

So perhaps the issue type should be updated. However, the root cause is still unclear — it might be related to a Windows Update or some other application conflict. 🤔

[choneas]

After some research, I think I’ve found a solution.

With the help of an LLM, I tried running:

sudo net stop winnat   # run as Administrator without `sudo` if `sudo` isn't enabled

After stopping winnat, I launched the official FE again and it successfully entered the main window. The enhanced version worked as well. Then I checked the excluded port ranges:

netsh interface ipv4 show excludedportrange protocol=tcp

Protocol tcp Port Exclusion Ranges

Start Port    End Port
----------    --------
      1136        1235
      1236        1335
      1336        1435
      1572        1671
      1674        1773
      2869        2869
      5357        5357
     50000       50059     *
     59100       59100     *

* - Administered port exclusions.

To my surprise, the previously reserved ports (8820–8919) disappeared. After restarting the computer (winnat automatically started again), FE continued to work fine.

If this is helping to you, you can try to enable winnat again.

I suspect this behavior may be related to enabling Hyper-V, although I haven’t disabled it. Maybe anyone can also try doing this. 🎉?

[auto-yui-patch]

That's great! At least we’ve found one reason, though there could be several other scenarios causing port conflicts. Let’s add these to the README.

So, if your FE is crashing on startup:

---

• Check logs by running Fiddler Everywhere.exe from the terminal. Pay special attention to the following line. (it’s omitted in the official, non-patched version of Fiddler Everywhere.)

  Server error log during start: System.IO.IOException: Failed to bind to address http://localhost:8868.
  

  If you see this, it's completely unrelated to the patch. You should see the same issue with the non-patched official FE. Confirm this.

• Check Fiddler Everywhere logs in %AppData%\Fiddler Everywhere\logs\

• Check Administered port exclusions to see if port 8868 is restricted. You can check it with:

  netsh interface ipv4 show excludedportrange protocol=tcp
  

• If port 8868 is restricted,

  • You should also see the same issue with the non-patched official FE. Confirm this.
  • You can try removing port 8868 from Administered port exclusions.

---

Do you agree? @choneas

[choneas]

Yes. In addition, maybe you can try running
cmd net stop winnat
with administrator privileges to see if that resolves the issue. 🧐

Apologies for not having much time recently, which has delayed the closure of this issue

[soldier-cv]

When I encountered an issue where the software wouldn't open, I conducted the following tests: 1. Downloaded the official software from the website --> it worked; 2. disabled the firewall and ran with administrator privileges --> the issue persisted; 3. Deleted the software directory, unzipped the downloaded zip file again, and ran it again --> it worked. This phenomenon seems to be that the unzipped program modified some content in the directory after running, causing subsequent access issues?

I hope to be able to provide help,thx