CER File Extension

What is CER file?

CER is a server file used for storing website signed certificates. Such certificates assure the webiste is genuine and can be trusted. Certificate also allows encrypted connection to the website using HTTPS and SSL protocols for secure browsing.

The process of obtaining a certificate

In order to apply for a certificate, user must contact the authority that issues the certificate. In most situations the best course of action is to contact the company that hosts our website and ask for assistance. Certificate issuing process comprises of the following steps:

1. Certificate registration – formal certificate request
2. Payment – payment for the certificate (typically charged on annual basis)
3. Choosing a domain – user must choose the domain for which the certificate is to be issued
4. Verification – formal verification to assure the identity of the person or organization that request a certificate
5. Issuing of the certificate – certificate is generated and passed to the requester
6. Certificate installation.

Programs which support CER file extension

The list that follows enumerates programs compatible with CER files, divided into 3 categories based on operating system on which they are available. Files with CER suffix can be copied to any mobile device or system platform, but it may not be possible to open them properly on target system.

Updated: 01/18/2023

How to open file with CER extension?

Problems with accessing CER may be due to various reasons. On the bright side, the most encountered issues pertaining to Internet Security Certificate files aren’t complex. In most cases they can be addressed swiftly and effectively without assistance from a specialist. The following is a list of guidelines that will help you identify and solve file-related problems.

Step 1. Download and install Microsoft Internet Explorer

The main and most frequent cause precluding users form opening CER files is that no program that can handle CER 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, Adobe Acrobat, Adobe Reader, Mozilla Firefox) and download it from appropriate source and install on your system. The full list of programs grouped by operating systems can be found above. The safest method of downloading Microsoft Internet Explorer installed is by going to developer’s website (Microsoft Corporation) and downloading the software using provided links.

Step 2. Update Microsoft Internet Explorer to the latest version

If the problems with opening CER 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. Sometimes software developers introduce new formats in place of that already supports along with newer versions of their applications. This can be one of the causes why CER files are not compatible with Microsoft Internet Explorer. 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. Assign Microsoft Internet Explorer to CER files

If the issue has not been solved in the previous step, you should associate CER files with latest version of Microsoft Internet Explorer you have installed on your device. The next step should pose no problems. The procedure is straightforward and largely system-independent

The procedure to change the default program in Windows

• Right-click the CER file and choose Open with option
• Select Choose another app → More apps
• The last step is to select Look for another app on this PC option supply the directory path to the folder where Microsoft Internet Explorer is installed. Now all that is left is to confirm your choice by selecting Always use this app to open CER files and clicking OK.

The procedure to change the default program in Mac OS

• From the drop-down menu, accessed by clicking the file with CER extension, select Information
• Open the Open with section by clicking its name
• Select the appropriate software and save your settings by clicking Change all
• If you followed the previous steps a message should appear: This change will be applied to all files with CER extension. Next, click the Continue button to finalize the process.

Step 4. Check the CER for 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 CER file. Being unable to access the file can be related to various issues.

1. The CER may be infected with malware – make sure to scan it with an antivirus tool.

Should it happed that the CER is infected with a virus, this may be that cause that prevents you from accessing it. Immediately scan the file using an antivirus tool or scan the whole system to ensure the whole system is safe. If the CER file is indeed infected follow the instructions below.

2. Ensure the file with CER extension is complete and error-free

If you obtained the problematic CER file from a third party, ask them to supply you with another copy. During the copy process of the file errors may occurred rendering the file incomplete or corrupted. This could be the source of encountered problems with the file. If the CER file has been downloaded from the internet only partially, try to redownload it.

3. Check if the user that you are logged as has administrative privileges.

There is a possibility that the file in question can only be accessed by users with sufficient system privileges. Log out of your current account and log in to an account with sufficient access privileges. Then open the Internet Security Certificate file.

4. Check whether your system can handle Microsoft Internet Explorer

The operating systems may note enough free resources to run the application that support CER files. Close all running programs and try opening the CER file.

5. Verify that your operating system and drivers are up to date

Regularly updated system, drivers, and programs keep your computer secure. This may also prevent problems with Internet Security Certificate files. It may be the case that the CER files work properly with updated software that addresses some system bugs.

Do you want to help?

If you have additional information about the CER file, we will be grateful if you share it with our users. To do this, use the form here and send us your information on CER file.