Javascript has never been turned off for users by default. You may have read a thread saying Java has been disabled, which is correct, but Java and Javascript aren't related technologies at all.

If you want to turn Javascript on, please do the following:

• Type about:support into your address bar, press Enter
• Accept the warning
• Search for javascript.enabled
• Make sure the value is true. (Double click it if it is not)

If this fails to work, Reset Firefox Refresh Firefox - reset add-ons and settings

Thanks, Tyler. I am indeed easily confused about tech things, but I was writing about JavaScript, not Java. Here is the thread I referenced saying it's turned off by default: https://support.mozilla.org/en-US/questions/990010?esab=a&s=javascript+gmail+standard+view&r=5&as=s

I have searched "JavaScript" and it is enabled. To try your easy solution, I Reset FF. Unfortunately it didn't work. JavaScript appears to be enabled, but Gmail attachments still won't open, still get that error message. (Also, just updated to FF 28.) Other suggestions? Thank you.

Also, why can't this be restored in an option instead of having to type in code?

There is nothing on that thread that says Javascript is turned off by default. to quote: "In Firefox 23, as part of an effort to simplify the Firefox options set and protect users from unintentially damaging their Firefox, the option to disable JavaScript was removed from the Firefox Options window.

However, the option to disable JavaScript was not removed from Firefox entirely. You can still access it from about:config or by installing an add-on. "

The UI checkbox to disable Javascript was removed, but the option still exists in about:config (which isn't code btw, it's just preferences), nor was Javascript turned off by default, in fact the opposite is true, it is enabled by default with the option to disable it made a little more difficult to find, as only advanced users need to disable Javascript.

Please try to clear the cache and cookies for gmail, let's see if those are causing problems. Clear cookies and site data in Firefox, How to clear the Firefox cache

Diego, those solutions have either already been posted, or have no bearing on this user's problems.

Thanks, guys. OK, thinking about this didn't make sense. So I decided to troubleshoot all aspects. I now believe that several attachments sent to me by one client are corrupted from her end. Attachments from several other folks do open! So sorry to waste your time, and very sad that I wasted so much of mine. I think this thread should be deleted. Thanks again.

No worries, glad you figured out the cause.

One day I am watching videos on Amazon and am on FB and suddenly and mysteriously my javascript is disabled and not working the very next day. I did not do anything! So I end up here read your posts, tried the easy way out first, empty the cache and walla I am back in business. Thanks ya'll! KUDOS

Tyler, your set of steps (prior to the 'Reset') do NOT work. There is no such option or section in FF 30 and higher as " javascript.enabled."

" Type about:support into your address bar, press Enter

   Accept the warning
   Search for javascript.enabled
   Make sure the value is true. (Double click it if it is not) "

I have not yet done a full Reset, so I'm not sure if that's the issue, or just that the option may be in a different place now. Anyway, some Javascript pages won't render, so I may try a Reset.

hmfic, there should be such an option (in Firefox 31, 30, 29, 28, and so on). If you don't have it, I suggest a reset since something else is wrong with your profile then.

hmfic are you typing in javascript.enabled or copy and pasting this as it could have a space before if not careful.

No, you've just got the wrong line/command: You said, "Type about:support into your address bar, press Enter "

Instead, it should be: "about:config" and then you have to click on "I promise I will be careful." Maybe in earlier versions, it was "about:support," but in 30 and higher, it is not; you have to use "about:config" - FYI.

• http://kb.mozillazine.org/about:config