With the debugger on.... it works but slow. Debugger off, issue as described above. Unfortunately I have no idea how to use the debugger.

This doesn't run for some reason:

<script language=JAVASCRIPT>MainFrame.location.href = 'serial.php?serial=ABCDEFGHIJK';</script>

Try this :

<script type="text/javascript">MainFrame.location.href = 'serial.php?serial=ABCDEFGHIJK';</script>

Ref. https://developer.mozilla.org/docs/Web/HTML/Element/script

Thanks for looking into this jscher2000. I made the change but it unfortunately does not make a difference. Where can I check for such errors in firefox to see if I can get more clues?

This is difficult for me to test, obviously. I don't see any specific error message explaining why the iframe href isn't changing. In case the problem is that Firefox needs to wait for the page to load before executing the change, how about something like this:

<script type="text/javascript"> document.addEventListener('load', function(){MainFrame.location.href = 'serial.php?serial=ABCDEFGHIJK'}); </script>

If that doesn't help, check out the resources here: Where to go for developer support.

The script is inside a PHP script and is echo'd:

echo "<script type=text/javascript>MainFrame.location.href = 'serial.php?serial=".$_REQUEST["serial"]."';</script>";

Reading up now how that coda may have to be adjusted as a script within a PHP script https://stackoverflow.com/questions/1164130/how-to-output-javascript-with-php

Will keep experimenting with it, at least you got me looking in the right direction so many thanks so far :)

I tried this serial number that showed in a Google search and that works: W88401231AX

• https://appleserialnumberinfo.com/Desktop/serial.php?serial=W88401231AX

You can try these steps in case of issues with web pages:

You can reload web page(s) and bypass the cache to refresh possibly outdated or corrupted files.

• hold down the Shift key and left-click the Reload button
• press "Ctrl + F5" or press "Ctrl + Shift + R" (Windows,Linux)
• press "Command + Shift + R" (Mac)

Clear the Cache and remove the Cookies from websites that cause problems via the "3-bar" Firefox menu button (Options/Preferences).

"Remove the Cookies" from websites that cause problems:

• Options/Preferences -> Privacy & Security
  Cookies and Site Data -> Manage Data

"Clear the Cache":

• Options/Preferences -> Privacy & Security
  Cookies and Site Data -> Clear Data -> Cached Web Content: Clear

Start Firefox in Safe Mode to check if one of the extensions ("3-bar" menu button or Tools -> Add-ons -> Extensions) or if hardware acceleration is causing the problem.

• switch to the DEFAULT theme: "3-bar" menu button or Tools -> Add-ons -> Themes
• do NOT click the "Refresh Firefox" button on the Safe Mode start window

• https://support.mozilla.org/en-US/kb/troubleshoot-firefox-issues-using-safe-mode
• https://support.mozilla.org/en-US/kb/troubleshoot-extensions-themes-to-fix-problems

You can remove all data stored in Firefox from a specific domain via "Forget About This Site" in the right-click context menu of an history entry ("History -> Show All History" or "View -> Sidebar -> History").

Using "Forget About This Site" will remove all data stored in Firefox from this domain like history and cookies and passwords and exceptions and cache, so be cautious. If you have a password or other data from that domain that you do not want to lose then make sure to backup this data or make a note.

You can't recover from this 'forget' unless you have a backup of involved files.

If you revisit a 'forgotten' website then data from that website will be saved once again.

• https://support.mozilla.org/en-US/kb/delete-browsing-search-download-history-firefox

No matter how I massage the quotes it works on pre-67 firefox and other browsers but not firefox 67. Currently have this:

echo "<script type='text/javascript'>MainFrame.location.href = 'serial.php?serial=".$_REQUEST["serial"]."';</script>";

Tested with your suggested code as well jscher2000

<script type="text/javascript"> document.addEventListener('load', function(){MainFrame.location.href = 'serial.php?serial=ABCDEFGHIJK'}); </script>

(of course replacing "?serial=xxx" with the PHP script and experimenting with the quotes) but that did not resolve it. It actually caused the same issue in pre-67 firefox as well.

I appreciate the help. The issue was resolved by a developer.

Yes, the new approach makes a lot more sense!