This site will have limited functionality while we undergo maintenance to improve your experience. If an article doesn't solve your issue and you want to ask a question, we have our support community waiting to help you at @FirefoxSupport on Twitter and/r/firefox on Reddit.

Search Support

Avoid support scams. We will never ask you to call or text a phone number or share personal information. Please report suspicious activity using the “Report Abuse” option.

Learn More

Running Mozilla Foxfire, we get error message:Microsoft Visual C++ Runtime Library. Assertion failed. Program File:common\npn_gate.cpp Expression:pPluginShim.

When running Mozilla Foxfire we get the error message listed in question. It asks: For information on how your program can cause assertion failure, see Visual C++ documentation on asserts (Pree retry to debug the application - JLT must be enabled. Then offers "Abort" - "Retry" - "Ignore". I do not know what this is telling me to do. Where is Visual C++ documentation on asserts. What do I need to do to keep from getting this error message?

When running Mozilla Foxfire we get the error message listed in question. It asks: For information on how your program can cause assertion failure, see Visual C++ documentation on asserts (Pree retry to debug the application - JLT must be enabled. Then offers "Abort" - "Retry" - "Ignore". I do not know what this is telling me to do. Where is Visual C++ documentation on asserts. What do I need to do to keep from getting this error message?

All Replies (1)

In the past, this issue was associated with the Flash player's protected mode, and particularly with out-of-date RealPlayer-related add-ons that interacted poorly with Flash 11.3 and higher.

To see whether you are experiencing a Flash-related interaction, try this: temporarily disable "protected mode" as described in this support article from Adobe under the heading "Last Resort": Adobe Forums: How do I troubleshoot Flash Player's protected mode for Firefox?

If that bypasses the error, check your other add-ons and remove, disable, or update them. Then allow Flash to run in protected mode as designed, restart Firefox, and test again.

orange Firefox button (or Tools menu) > Add-ons > Plugins category
orange Firefox button (or Tools menu) > Add-ons > Extensions category