On some sites, charts are drawn using the Flash plugin (called the Shockwave Flash plugin when installed in Firefox). Do you know whether the site you're talking about requires Flash? When you use the page in another browser and right-click the part of the chart that is missing in Firefox, the Flash plugin has a distinct context menu different from the regular Firefox right-click context menu. I think it mentions Flash near the bottom.

If you need Flash, see:

• Install the Flash plugin to view videos, animations and games
• Why do I have to click to activate plugins?

If it's not a Flash issue:

Do you want to share a link to a page that has this problem?

Otherwise, if a site is generally known to work in Firefox, these are standard suggestions to try when it stops working normally:

Double-check content blockers: Firefox's Tracking Protection feature and extensions that counter ads and tracking may break websites that weren't built to operate normally without the blocked components.

Do you see a shield icon toward the left end of the address bar, near the lock icon? More info on managing the Tracking Protection feature in this article: What happened to Tracking Protection?.

Extensions such as Adblock Plus, Blur, Disconnect, Ghostery, NoScript, Privacy Badger, uBlock Origin or uMatrix should provide toolbar buttons to manage blocked content in a page. There may or may not be a number on the icon indicating the number of blocked items; you may need to click the button to see what's going on and test whether you need to make an exception for this site.

Cache and Cookies: When you have a problem with one particular site, a good "first thing to try" is clearing your Firefox cache and deleting your saved cookies for the site.

(1) Clear Firefox's Cache

See: How to clear the Firefox cache

If you have a large hard drive, this might take a few minutes.

(2) Remove the site's cookies (save any pending work first). While viewing a page on the site, try either:

• right-click (on Mac Ctrl+click) a blank area of the page and choose View Page Info > Security > "Clear Cookies and Site Data"
• (menu bar) Tools > Page Info > Security > "Clear Cookies and Site Data"
• click the padlock or "i" icon in the address bar, then the ">" button, then More Information, and finally the "Clear Cookies and Site Data" button

In the dialog that opens, you will see one or more matches to the current address so you can remove the site's cookies individually without affecting other sites.

Then try reloading the page. Does that help?

Testing in Firefox's Safe Mode: In its Safe Mode, Firefox temporarily deactivates extensions, hardware acceleration, and some other advanced features to help you assess whether these are causing the problem.

If Firefox is not running: Hold down the Shift key when starting Firefox. (On Mac, hold down the option/alt key instead of the Shift key.)

If Firefox is running: You can restart Firefox in Safe Mode using either:

• "3-bar" menu button > "?" Help > Restart with Add-ons Disabled
• (menu bar) Help menu > Restart with Add-ons Disabled

and OK the restart.

Both scenarios: A small dialog should appear. Click "Start in Safe Mode" (not Refresh).

Any improvement?

Thanks for the prompt and detailed reply. I replied by email, didn't realise it was a no-reply address. Now pasted in here.

I had tried most of these, results are:

Right clicking the chart in Edge gives no references to Flash.

I am reluctant to share a link as the page contains personal financial information.

Disabling content blocking for this site made no difference.

AdblockPlus is not blocking any ads on the site.

Cache and site cookies cleared - no change.

Ran in safe mode - no change.

So I'm afraid these didn't work. Do you have any other suggestions?

Thanks and regards

Geoff

Hi Geoff., if the page has personal information, it probably means we couldn't view it without logging into an account, so unless they have a general demo page, we'll have to rely on you and the site's support services to figure out what's going on.

If I encountered this problem myself, I would check:

(A) Any error messages?

You can check for messages in Firefox's Web Console. You can open the Web Console in the lower part of the tab using either:

• "3-bar" menu button > Web Developer > Web Console
• (menu bar) Tools > Web Developer > Web Console
• (Windows) Ctrl+Shift+k

Then reload the page in the upper part of the tab and watch for error or security messages. (The lines with triangle icons generally are not significant unless you suspect a style rule problem.) Anything that sounds like it could be relevant?

As you interact with different parts of the page, you may see different messages.

(B) Any failed requests?

To open the Network Monitor it the lower part of the tab, you can use either:

• "3-bar" menu button > Web Developer > Network
• (menu bar) Tools > Web Developer > Network
• (Windows) Ctrl+Shift+e

When the tools are already open, click "Network" along the top bar of the tools.

When you reload the page in the top part of the tab, Firefox should start listing all the files it is requesting, along with information about whether the request was successful. Codes of 400 or higher, or missing codes in the left column, can indicate a problem.

Thanks again for your suggestions.

I have tried, over the last few days, several changes to the Privacy and Security options, having seen the Web Console. None of them worked and I also had a problem with another website when I completed a form on a webpage and tried to submit it.

I was beginning to despair and thinking of ditching Firefox, but had one last go this morning. More changes to the options and it worked! Reset a blocking option and it still works. I have no idea what I did differently (I've tried so many...)

I am still receiving warnings on the console, now reduced to: Cross-Origin Request Blocked: The Same Origin Policy disallows reading the remote resource at https://ff.kis.v2.scr.kaspersky-labs.com/FBB552F4-9112-8647-A506-73B8E9824975/6790FAEC-4752-DE44-8862-48642259D5C1/longpooling?get&nocache=14a86. (Reason: CORS request did not succeed). Followed by several repetitions of: unreachable code after return statement.

Clearly not ideal, and it causes a noticeable delay in response times. Have you any suggestions on how to eliminate them?

Thanks Geoff

Sounds like kaspersky is part of the cause blocking the page. Did you disable kaspersky and see what happens? If it works then kaspersky is the problem and you should get a better security software. For Windows 10 you should try the Defender that comes with it first. That is free and works just fine.

I disabled Kaspersky - or at least as much as I could, the anti-virus component continued to load and run. When I tried to open the chart I could see it was trying to contact Kaspersky but presumably the now missing software prevented that, and the attempted load timed out. So that was worse than my original problem.

Do you have any other suggestions? If not I can contact Kaspersky for their input.

Re the second half of your post, Kaspersky has been regarded by independent Windows techies as the best security software for several years now.