PAC File Extension

What is PAC file?

A .PAC file, also known as the Proxy Auto-Config file, is a configuration file that is used by the web browser for automating the proxy server connection setting. The PAC file contains a single function written in Java script to specify the mode of connection to be established by the web browser to access the specified URL. The mode of connection specified by the PAC file can choose either a direct mode to access the URL directly or through a proxy server. Further, the PAC file is created and edited using a simple text editor supported on Windows and MAC OS.   

Programs which support PAC file extension

The list that follows enumerates programs compatible with PAC files, divided into 3 categories based on operating system on which they are available. Files with PAC extension, just like any other file formats, can be found on any operating system. The files in question may be transferred to other devices, be it mobile or stationary, yet not all systems may be capable of properly handling such files.

Updated: 03/05/2024

How to open file with PAC extension?

There can be multiple causes why you have problems with opening PAC files on given system. Fortunately, most common problems with PAC files can be solved without in-depth IT knowledge, and most importantly, in a matter of minutes. The list below will guide you through the process of addressing the encountered problem.

Step 1. Download and install Microsoft Internet Explorer

The main and most frequent cause precluding users form opening PAC files is that no program that can handle PAC files is installed on user’s system. This one is an easy one. Select Microsoft Internet Explorer or one of the recommended programs (for example, Mozilla Firefox, Safari) and download it from appropriate source and install on your system. Above you will find a complete listing of programs that support PAC files, classified according to system platforms for which they are available. If you want to download Microsoft Internet Explorer installer in the most secured manner, we suggest you visit Microsoft Corporation website and download from their official repositories.

Step 2. Update Microsoft Internet Explorer to the latest version

If the problems with opening PAC files still occur even after installing Microsoft Internet Explorer, it is possible that you have an outdated version of the software. Check the developer’s website whether a newer version of Microsoft Internet Explorer is available. Software developers may implement support for more modern file formats in updated versions of their products. If you have an older version of Microsoft Internet Explorer installed, it may not support PAC format. All of the file formats that were handled just fine by the previous versions of given program should be also possible to open using Microsoft Internet Explorer.

Step 3. Associate Proxy Auto-Config Format files with Microsoft Internet Explorer

If the issue has not been solved in the previous step, you should associate PAC files with latest version of Microsoft Internet Explorer you have installed on your device. The process of associating file formats with default application may differ in details depending on platform, but the basic procedure is very similar.

Change the default application in Windows

• Clicking the PAC with right mouse button will bring a menu from which you should select the Open with option
• Next, select the Choose another app option and then using More apps open the list of available applications
• To finalize the process, select Look for another app on this PC entry and using the file explorer select the Microsoft Internet Explorer installation folder. Confirm by checking Always use this app to open PAC files box and clicking OK button.

Change the default application in Mac OS

• By clicking right mouse button on the selected PAC file open the file menu and choose Information
• Proceed to the Open with section. If its closed, click the title to access available options
• Select the appropriate software and save your settings by clicking Change all
• Finally, a This change will be applied to all files with PAC extension message should pop-up. Click Continue button in order to confirm your choice.

Step 4. Ensure that the PAC file is complete and free of errors

You closely followed the steps listed in points 1-3, but the problem is still present? You should check whether the file is a proper PAC file. It is probable that the file is corrupted and thus cannot be accessed.

1. Verify that the PAC in question is not infected with a computer virus

If the PAC is indeed infected, it is possible that the malware is blocking it from opening. Scan the PAC file as well as your computer for malware or viruses. If the scanner detected that the PAC file is unsafe, proceed as instructed by the antivirus program to neutralize the threat.

2. Verify that the PAC file’s structure is intact

If the PAC file was sent to you by someone else, ask this person to resend the file to you. It is possible that the file has not been properly copied to a data storage and is incomplete and therefore cannot be opened. When downloading the file with PAC extension from the internet an error may occurred resulting in incomplete file. Try downloading the file again.

3. Ensure that you have appropriate access rights

There is a possibility that the file in question can only be accessed by users with sufficient system privileges. Switch to an account that has required privileges and try opening the Proxy Auto-Config Format file again.

4. Verify that your device fulfills the requirements to be able to open Microsoft Internet Explorer

If the systems has insufficient resources to open PAC files, try closing all currently running applications and try again.

5. Ensure that you have the latest drivers and system updates and patches installed

Regularly updated system, drivers, and programs keep your computer secure. This may also prevent problems with Proxy Auto-Config Format files. It may be the case that the PAC files work properly with updated software that addresses some system bugs.

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