Troubleshooting problems connecting to POPFile's UI can be difficult as there are many reasons why you could fail to connect, ranging from proxies and ad blockers to firewalls.

Although every person's setup will be different, it's generally a good idea to start with the basics and eliminate the obvious issues in a methodical manner. Try stepping thru each of the following to identify the problem on your system:

1. Make sure POPFile is really running. On Windows systems check the Task Manager (Ctrl, Alt, Del) and look for an instance of popfilef.exe, popfileif.exe, popfileb.exe or popfileib.exe. If you do not find any of these programs then POPFile is not running. Start POPFile and try connecting to the UI after it starts up (allow a minute or so for it to load the corpus and other housekeeping).
2. Confirm you are using the correct link to access the UI. The correct link for those who have not changed the User Interface Web Port from the default of 8080 is http://localhost:8080/ (Note that the http:// portion is not optional, you must include it ).
3. If the above link does not work, try the following alternative link http://127.0.0.1:8080/. If this link works but http://localhost:8080/ does not then there may be a problem with the hosts file. The hosts file should include a line like this

   127.0.0.1	localhost

4. Note that on Windows systems you can use either space or tab characters to create the gap between 127.0.0.1 and localhost (do not use a mixture of spaces and tabs). The default locations of the hosts file on Windows are:

   Windows 7      =   C:\WINDOWS\SYSTEM32\DRIVERS\ETC
   Windows Vista  =   C:\WINDOWS\SYSTEM32\DRIVERS\ETC
   Windows XP     =   C:\WINDOWS\SYSTEM32\DRIVERS\ETC
   Windows 2000   =   C:\WINNT\SYSTEM32\DRIVERS\ETC
   Windows 98/ME  =   C:\WINDOWS

   1. As an alternative to editing the hosts file, access the POPFile UI then go to the ADVANCED page. There is a long column of POPFile parameters on that page. Find the one labelled “bayes_localhostname” and enter 127.0.0.1 into the box (the default setting is an empty box). Click the “Update” button at the bottom of that column to save this change. Now shutdown POPFile and re-start it - the system tray icon will now use http://127.0.0.1:8080 to access the UI.
5. Check for other programs using port 8080. Shutdown POPFile, then open a DOS box and issue the netstat command, e.g.,

   netstat -an > output.txt
   start notepad.exe output.txt

   1. Check the output of the netstat command for anything listening on port 8080, for example, the sample netstat output below shows two instances of port 8080.

      Active Connections
      
       Proto  Local Address          Foreign Address        State
       TCP    0.0.0.0:25             0.0.0.0:0              LISTENING
       TCP    0.0.0.0:5679           0.0.0.0:0              LISTENING
       TCP    0.0.0.0:106            0.0.0.0:0              LISTENING
       TCP    0.0.0.0:110            0.0.0.0:0              LISTENING
       TCP    0.0.0.0:123            0.0.0.0:0              LISTENING
       TCP    0.0.0.0:8080           0.0.0.0:0              LISTENING
       TCP    0.0.0.0:1417           0.0.0.0:0              LISTENING
       TCP    0.0.0.0:1172           0.0.0.0:0              LISTENING
       TCP    0.0.0.0:1684           0.0.0.0:0              LISTENING
       TCP    0.0.0.0:162            0.0.0.0:0              LISTENING
       TCP    0.0.0.0:5106           0.0.0.0:0              LISTENING
       TCP    0.0.0.0:5107           0.0.0.0:0              LISTENING
       TCP    0.0.0.0:5108           0.0.0.0:0              LISTENING
       TCP    127.0.0.1:111          0.0.0.0:0              LISTENING
       TCP    127.0.0.1:1392         0.0.0.0:0              LISTENING
       TCP    127.0.0.1:4473         0.0.0.0:0              LISTENING
       TCP    127.0.0.1:8080         0.0.0.0:0              LISTENING
       TCP    127.0.0.1:4785         0.0.0.0:0              LISTENING
       TCP    192.168.1.2:137        0.0.0.0:0              LISTENING
       TCP    192.168.1.2:138        0.0.0.0:0              LISTENING
       TCP    192.168.1.2:139        0.0.0.0:0              LISTENING
       UDP    0.0.0.0:123            *:*
       UDP    0.0.0.0:162            *:*
       UDP    127.0.0.1:1392         *:*
       UDP    127.0.0.1:4473         *:*
       UDP    127.0.0.1:4785         *:*
       UDP    192.168.1.2:137        *:*
       UDP    192.168.1.2:138        *:*

6. If you find that port 8080 is in use, then that's a real good indicator that some other piece of software installed on your machine is already using port 8080. You should change POPFile's port to something other than 8080;
   1. Shutdown POPFile.
   2. Open a DOS box and switch to the POPFile install directory (normally this will be c:\program files\popfile), e.g.,

      cd "\program files\popfile"

   3. Start POPFile in the foreground with the special switch ui_port set to the new port you want POPFile to use (like maybe 8088);

      perl popfile.pl --set ui_port=8088

   4. Now try accessing the UI using the new port in your link, http://127.0.0.1:8088/ (change to the port you selected if not 8088).
7. Or adjust the port via the User interface web port in http://127.0.0.1:8080/configuration before shutting down POPFile,
8. Make sure your browser isn't using a proxy. For IE you can check the settings at Tools/Internet Options/Connections Tab/Lan Settings button. If a proxy is being used, make sure that “Bypass proxy for local addresses” is checked.
9. If you are running a personal firewall, make certain you have configured it to allow popfile*.exe (perl.exe or wperl.exe in older version of POPFile) permission to access ports 8080 and 110. See the detailed instructions in POPFile Manual.
10. Try disabling any virus scanner you may have operating on your machine.
11. Try disabling or removing any ad blockers you may have operating on your machine.
12. Obtain Ad-aware from Lavasoft and/or Spybot Search & Destroy and run it to remove all spyware from your machine. Some spyware causes issues with your TCP/IP stack and may make it impossible to connect to POPFile.
13. Confirm your TCP/IP stack is operating correctly. LSP Fix utility, it is a free utility to repair damaged Winsock settings. Windows XP SP2 is supposed to repair LSP damage automatically, this utility was written before XP SP2. It appears safe to use on SP2.
14. If LSPFix doesn't help, WinSock XP Fix might (Windows XP only). This method has not been tested by POPFile developers. If you are using XP SP2 running this at the command prompt, is supposed to do same thing:

    netsh winsock reset

15. Microsoft lists a bunch of more heavy duty techniques you can try. In the end it seems comes down to uninstalling Window's TCP/IP Protocol and reinstalling it. It doesn't sound like you need your Windows disk but you might find it just in case if your computer came with one.
16. If nothing has worked and you are using Windows XP, open the command prompt and run sfc /scannow. You will need your Windows CD (or Recovery CD) if your computer came with one. This utility scans for Windows files that have been modified from the original and replaces them. This will probably require you to run Windows Update again to download updates. Be sure your firewall is working and get those updates before you use the internet again since your computer is not protected with the latest updates.
17. The last method to try (other than reinstalling Windows) is a Windows XP Repair Install. You must be very careful and follow the instructions exactly and read each screen carefully to prevent from loosing all your files. You will need a Windows XP CD (an Operating System Restore disk will not work). This option replaces all your Windows files back to the original install state, you will have to download a lot of Windows updates before your computer is safe to use on the internet again. Be sure you have a good backup of your files just in case before you try this, it is easy to make a mistake telling install to format your drive. Follow the instructions on the linked website carefully. If you are not comfortable doing this, do not try it, find someone who knows what they are doing. The POPFile developers will not be responsible for any data loss that may occur.
18. If all of the above troubleshooting does not solve the problem, post to the POPFile Help Forum for further help.