Does it matter how you open the file? For example:

• double-click the file in Finder
• use the File > Open File dialog
• other methods...

Does it matter whether the files were saved from the web, or created by you for eventual display on the web, or supplied with locally installed software (e.g., help files) that were purely designed for local use?

The files in question are all HTML ones I've created locally.

I've tried dragging and dropping, my usual way.

I've tried opening them with the file open menu command.

I've tried double-clicking them with the Application" setting for Firefox document set to Firefox.

All of my HTML files are validated as HTML Strict 4.01 and created by my HTML editor. I use them both on the web and locally. None are files downloaded from the web.

They display normally in Chrome and Safari and on W7 Chrome.

Hmm, I'm not seeing a problem in 32-bit Firefox on Windows 7 with Multiprocess disabled. It's not disabled on purpose, but due to incompatible extensions. Could you check that factor:

Are you using Multiprocess (e10s)?

Multiprocess creates a second firefox.exe or plugin-container.exe process to isolate the web content from the browser UI. This occasionally causes glitches due to interprocess communication issues. You can check whether you have this feature turned on as follows. Either:

• "3-bar" menu button > "?" button > Troubleshooting Information
• (menu bar) Help > Troubleshooting Information
• type or paste about:support in the address bar and press Enter/Return

In the first table on the page, check the row for "Multiprocess Windows" and see whether the number on the left side of the fraction is greater than zero. If so, you are using e10s.

If you are using e10s:

To help evaluate whether that feature is causing problems, you could turn it off as follows:

(1) In a new tab, type or paste about:config in the address bar and press Enter/Return. Click the button promising to be careful.

(2) In the search box above the list, type or paste autos and pause while the list is filtered

(3) Double-click the browser.tabs.remote.autostart.2 preference to switch the value from true to false

Note: the exact name of the preference may vary, but it will start with browser.tabs.remote.autostart

At your next Firefox startup, it should run in the traditional way. Any difference?

Try to set security.sandbox.content.level = 0 on the about:config page

Bug 1196384 - [meta] Cross-platform blockers for default-deny filesystem policy for content processes Bug 1149706 - [Meta] Remaining issues for content process sandboxing on the Mac

To jscher2000's reply:

I generated the troubleshooting information page and note that, in the first table in the "Multiprocess Windows" value was "0/2 (Disabled by add-ons)".

browser.tabs.remote.autostart.2 was true and I changed it to false and restarted Firefox. No change. Local HTML files aren't displayed no matter how opened/loaded.

I restarted in safe mode and my HTML pages displayed normally albeit not as I am accustomed to viewing them given the absence of addons.

After the restart in safe mode, the "Multiprocess Windows" value was still "0/2 (Disabled by add-ons)".

I saved copies of the raw and text versions of the "Troubleshooting Information" in safe mode. Would a copy of either or both help identify the addon(s) causing the problem? If yes, which or both?

To cor-el's reply:

security.sandbox.content.level was "1" and I set it to "0" and restarted Firefox. No change (my HTML files aren't displayed).

I restarted Firefox in safe mode.

See my reply to jscher2000 (above) regarding restarting in safe mode and the HTML files being displayed.

I reset security.sandbox.content.level back to "1".

I refreshed the troubleshooting information and the security.sandbox.content.level parameter was missing and "security.sandbox.content.tempDirSuffix" was reported as "{9124dbb7-8f5b-9240-9384-d9421714321b}". My HTML files displayed normally.

I saved copies of the raw and text versions of the "Troubleshooting Information" in safe mode. Would a copy of either or both help identify the addon(s) causing the problem? If yes, which or both?

Hi robin416, you wrote:

I restarted in safe mode and my HTML pages displayed normally albeit not as I am accustomed to viewing them given the absence of addons.

That's a very useful result. You probably have a sense of which extensions have the potential to block or filter out various kinds of page content and you could try making exceptions (if that's an option) or disabling them to see whether you can track down the critical one(s). You also could check their reviews on the Add-ons site to see whether there is a known new issue with file:// URLs.

jscher2000:

I'll try to except or disable extensions that may block or filter out page content but I expect to end up just dividing the addons list in two and disabling one half and restarting Firefox. Hopefully one half or the other will allow HTML content. Whichever half blocks HTML content, I'll divide in 2 again and restart and so on.

If you have an easier way to ID the culprit(s), let me know. I've my fingers crossed that it's just one addon.

I'll post here and to the relevant addon when I identify it.

By exception, do you mean exceptions as in NoSquint Plus addon's exceptions mechanism? I'm not sure which addons have such options.

For exceptions I'm thinking of the most common extensions like Adblock Plus, Ghostery, Privacy Badger, etc., which typically offer a toolbar button to manage what is blocked.

Another user narrowed it down to the NoScript extension. Do you use that one?

There is a thread about this on the NoScript forum: https://forums.informaction.com/viewtopic.php?f=7&t=22761

The consensus there is if you turned on "Allow local links" for Trusted sites, then file:/// doesn't load. You can turn that off here:

NoScript "S" button > Options > Advanced > Trusted mini-tab

See attached screenshot

Or:

(1) In a new tab, type or paste about:config in the address bar and press Enter/Return. Click the button promising to be careful.

(2) In the search box above the list, type or paste nosc and pause while the list is filtered

(3) If the noscript.allowLocalLinks preference is bolded and "user set" to true, double-click it to restore the default value of false

In my test, the results are instant: when this is on/true, files do not load, as soon as I set it back to off/false, back to normal.

Could you test that?

When we write the history of Internet web browsers, who will provide the date when web browsers no longer could open HTML files?

I admit to being so frustrated I Can't condense my question enough that someone will want to read All of it it and help me :-) going back to Firefox version 1.0, I Have always had the option to "SAVE PAGE" as an HTML file,So that I can open again and look at it on my local hard drive but now of course we have made it more complex by forcing it to be HTML. What I find most exasperating is that each thread I've ever found regarding this issue becomes convoluted, misdirected, and totally clogged up by people who want to help but can't seem to get past the idea that they must grill the questioner As to whether-or not they know what an HTML file is :-(

For the purpose of this inquiry,An HTML file is the file I just saved from Firefox.

That should clear up any question about whether I know how to open a file, or if I know what it takes to create an HTML file because I didn't create The file,Firefox did.

This is not new. why is everyone ducking it and why are those of us who used to use this feature as part of our business no longer able to earn a living?

Windows 7, Firefox version 50 I've tried chrome, latest version, i.e., latest version as well as Firefox in any one of a dozen other third-party browsers that are floating around the net. Curiously everyone of those browsers has a Built-in feature that I can use to save a webpage. But not one of them Is able to open the file I Just saved to let me look at it .I dusted off my windows XP file server. It's old but finally booted up to the desktop out of curiosity. Firefox version 44. still goes right out the web and opens up pages like I'm used to having things happen. So I choose file save, close Firefox, open up "my computer" drill down to that file that I just had Firefox create for me, double-click it, and holy smoke ! it opened the file. The exact same page that Windows 7 and Firefox 50 throws up on .Please? Those of us who've grown up with computers and its foibles, realize that there is no controlling entity to deal with this issue, but we still need to have the tools at our disposal to help us earn a living and kind of need a solution. .Six months ago I thought I'd buy a chrome book. Until the last few days I considered to be a rather silly implementation of a really weak operating system. However for six months I have been using the option to "save page" and recover the page at a later date. Imagine my surprise when I chose to work on my windows7 firefox pc, and it has "gone stupid" and useless on me?

The chrome book, which-uses the same version of chrome browser as I have on my Windows 7 PC, saves pages Effortlessly and has no Problem Opening HTML files that I save from Firefox version 50 on a Windows 7 PC. I guess I'm overreacting :-) but I think this is important.

Can anyone tell me how I can open up an HTML file, so that I can view the webpage as it was presented to me, I don't mean opening it with WordPad and examining the hypertext markup language am I the only person who saves webpages for future reference? :-)

When I go over the facts, I am actually pointed in the direction that Microsoft has done this. I say that because the chrome book using the same chrome browser as my Windows machine has no problems saving pages and opening them. Windows XP does not have any issues with opening HTML files with any web browser on the planet I'm going to be spending in wasting my time evaluating this issue through a Linux installation or a bootable CD.

I'd love to help anybody who has a problem, so if I get any clues I'll certainly post them but I really can't help the Admittedly "childish and immature" position that Mozilla better fix this , Or at least offer an explanation .All my searching and looking around keeps pointing to a security risk of opening HTML from a local file.

At a cost not to go any further, but I would like get some help :-) I'm getting impression that security risk is why Adobe flash and Microsoft's over light will no longer play with Firefox.

As it is right now if I come upon a page with a video file within it, I get a message that if I right click I can bypass the apparent security risk, and watch the video without any problems.

If no one is concerned about all of us opening our computers up to the Russians, Iranians, and North Koreans when we view a flash file, why not apply the same logic to opening an HTML file? I don't who does it so I can't point to any one but it would be okay with me if when I tried to open an HTML file I was warned, or nagged, that this might be a security problem "do I want to proceed?"

Those of you who read this are probably pretty burned out on me by now, and I'm sorry. I'm grateful for your time and it only works when people want to step up and help. So for 30 years I've appreciated out forms and people give of their time. I mean no offense by any implications in my "tone of voice" but it has taken me over an hour to whittle this down to a readable cry for help.

Those of you out there who are developing webpages, what are you using to take a final look at your creation? I know Microsoft is to give away fancy pants software, but when I create webpages I would use a text editor and then pop it open with Firefox.

Thank you all very much I hope the rest of the week is good to you

John

After my 2017-04-21 post to this thread, I stopped using Firefox in favor of Chrome and then didn't get around to finding the errant extension because the process is so tedious.

At the beginning of this month (June), I used Firefox on a local HTML page by mistake and, to my surprise, it displayed normally.

I'm on version 53.0.3 and, so far as I can tell, the issue that prevented any display of such pages has been resolved.

In the result, I don't know what exactly caused the problem but I'm delighted to be back using Firefox.

robin416 said

After my 2017-04-21 post to this thread, I stopped using Firefox in favor of Chrome and then didn't get around to finding the errant extension because the process is so tedious. At the beginning of this month (June), I used Firefox on a local HTML page by mistake and, to my surprise, it displayed normally. I'm on version 53.0.3 and, so far as I can tell, the issue that prevented any display of such pages has been resolved. In the result, I don't know what exactly caused the problem but I'm delighted to be back using Firefox.

I am pleased you are able to open html file with firefox now. can you do so with chrome or IE? I cannot.

just remember you have no promise that the next roll out version will still function like the version you now have, and if it does fail, to bad for you. help is not available. Never use Firefox in business application, because as with me, you could lose your customer base and your business because you trusted someone to be honest and provide support for you. at the least, archive v 50.03 that you are using now for the time when Mozilla screws you again.

wait, I -can- open html files because I am using firefox v11.00 but it is a drag to be nagged by mozilla repeatedly, even tho I have explicitly turned off any update option. something else firefox cannot do. follow its settings, so twice it has taken control and updated itself. Microsoft style....

I miss os/2 and its built in web browser. old, but at least IBM would stand behind its product and NEVER hang a customer out to dry like Mozilla has done here.

 Its an inane movie quote. but "who you gonna call? 

I am reading all of the help and ideas in this thread, and am a bit confused, by all the configuration changes recommended, and the running of test apps, and digging into deep holes in hopes of restoring a function that worked 20 years ago what happened to making the new version work whn installed?

I just cleared away my v11.0 and downloaded 53.03, or which ever is latest on Mozilla .org and it will not open an html file that it creates. so from here, Firefox is still baldly broken.

the only way to view an html file is to use a google Chromebook. are you listening Firefox? google is eating your lunch.

just google " how can I open a local html file and you will get 122 million results, not one of which says " use a web browser." because it no longer works. it is a sickness hen a simple function needs a youtube video to explain, and still it does not work...

browsers can save an html file, but they cannot open them. until this month or so, every web browser on earth could save an html file and open that very same file.

I know I am just one crybaby user who has no clout or leverage, but if one installs the latest Firefox and has to try all the "ideas" listed in this thread, Firefox is dead. and I wish I held the gun

this uppity , " are you sure its an html file" crap is worse than what poured out of windows forums for decades until MS woke up. people who need help don't need to be humiliated.

when a user asks why they cannot open an html file and they are grilled as to whether they know if it is a real html file, its time to throw the pc away,, and turn to Chromebook, which has never failed to open an html file, and maybe turn it into linux box.. either way, not being screwed by firefox is worth the effort.

asking around, it seems that the people smart enough to dump firefox and windows years ago for a linux distro are unaware of this issue, and seem to be laughing at the open source model, which hey have used successfully for decades.

firefox needs to close up shop until they learn how to listen and provide useful solutions.

Hi singlewc/John, I suggest you start a new thread about your HTML file problem. When this thread was started, there was a known issue with the NoScript extension that affected Firefox only when NoScript was running (i.e., there was not a problem in Firefox's Safe Mode). Your issue sounds completely different because it affects all of your browsers except, for some reason, a browser from several years ago.

You can start a new question using this link:

https://support.mozilla.org/questions/new

Scroll down past article suggestions to continue with the form.

Also, please do not start new lines with blank spaces, since that causes them to be parsed as preformatted blocks on this forum -- as you can see in your last reply, that makes long lines unreadable due to the need to scroll horizontally.

jscher2000 said

Hi singlewc/John, I suggest you start a new thread about your HTML file problem. When this thread was started, there was a known issue with the NoScript extension that affected Firefox only when NoScript was running (i.e., there was not a problem in Firefox's Safe Mode). Your issue sounds completely different because it affects all of your browsers except, for some reason, a browser from several years ago. You can start a new question using this link: https://support.mozilla.org/questions/new Scroll down past article suggestions to continue with the form. Also, please do not start new lines with blank spaces, since that causes them to be parsed as preformatted blocks on this forum -- as you can see in your last reply, that makes long lines unreadable due to the need to scroll horizontally.

 thank you,

sorry. I do not start lines with empty spaces. fact is, I use voice to dictate into these boxes, so the problem is not me.

I have posted this issue all over these support pages, to no avail, so why would doing it in more places yield a different result? no one will touch it, but each new post seeking help yields insinuations that I do not know what an html l fie is, and that I do not know how to open such a file and now the problem has no importance and offers no hope for help because I am using blank spaces in my posts?? When so when helpers actually address the issue instead of assassinating the knowledge base of the poster?

In reply to singlewc, I have no problem displaying either my local HTML files and their CSS as well as pages saved from Firefox itself on Firefox, Chrome and Safari.

robin416 said

In reply to singlewc, I have no problem displaying either my local HTML files and their CSS as well as pages saved from Firefox itself on Firefox, Chrome and Safari.

Thank you. no sarcasm intended at all  :-) I am glad it works for you.

A little time scrounging the net reveals that millions of users can no longer open a file created by any browser. They have no voice and no place to go for help. I will understand anyone who does not believe me, but its too much trouble to whine this much for an imaginary problem. :-)

I know I am just a complainer, but this is not my imagination, and it absolutely sucks that there is no place to go to get help.

my business is shut down and I cannot pay the mortgage until I learn how to view an html page. Not crazy about moving my entire business onto a Chromebook because google help is as bad as Mozilla. that is why I am sure my attitude is very poor. Big mistake to trust anyone or anything. Its not like the internet is of any use anyway <shrug>

Thanks for your input and experiences.

Create a new profile to test if your current profile is causing the problem.

See "Creating a profile":

• https://support.mozilla.org/en-US/kb/profile-manager-create-and-remove-firefox-profiles
• http://kb.mozillazine.org/Standard_diagnostic_-_Firefox#Profile_issues

If the new profile works then you can transfer files from a previously used profile to the new profile, but be cautious not to copy corrupted files to avoid carrying over problems.

• http://kb.mozillazine.org/Transferring_data_to_a_new_profile_-_Firefox

Note singlewc has their own recent support thread

• what has happened to firefox?? /questions/1162735

It probably makes sense to post any further answers to those questions in the above thread. I will tidy up the posts with the leading spaces in.

Just in case there are important answers made in recent threads it may be worth noting that at some point in the near future (No idea yet if days or weeks away ) we will move back to the mew Forum software and none of the posts made since the emergency rollback will be migrated to the new forum software. (They may be temporarily retained in a read only copy of the forum, but do not expect bookmarks and links, including any in emails you are sent to work directly)

singlewc said

I do not start lines with empty spaces. fact is, I use voice to dictate into these boxes, so the problem is not me.

Obviously speech-to-text software is very imperfect. Maybe when you use Preview (the button just to the right of Post) and see the problem you can fix it when it appears.

Back to your inability to open HTML files in any browser:

What happens when you try to open an HTML file from your computer in Firefox?

For example:

• If there is a specific error message, what is the message?

• If the page appears to be blank, try using View Source to confirm that the file contains the expected HTML code. Either:
  • Ctrl+u
  • right-click the page > View Page Source

• If the page contains the HTML code but appears blank, try turning off style rules to view it in an unstyled state: View menu > Page Style > No Style. (If you do not normally display the classic menu bar, you can activate it temporarily by tapping the Alt key or F10 function key.)