Are you running firewall or other security software?

In case of McAfee: see this article and follow the steps described. In case of any other security software, check the same page for known issues for your product. You might need to remove and add the Thunderbird enrty in allowed programs for the security software.

In case it doesn’t help, make sure Use system proxy settings is not selected in Options > Advanced > Network > Settings.

(The "chrome://messenger..." reference is an internal reference used in Mozilla products from the beginning, and has nothing to do with the Chrome browser.)

Hi Tonnes, On the options | Advanced | Network... | Settings... I have unticked the Use system proxy setting.... I have selected NO Proxy. There is now no delay. As yet don't know what the disadvantage of doing this??? Thanks for you help on that. Regards Princy 557

My view is that the computer may be infected by scripts. Maybe try searching the error message and run an antivirus scan.

Hi Princy, glad to see it helped, if I understood correctly.

I don’t think setting it to "No proxy" has any disadvantages. Unless an ISP requires to use it, most users should use a direct connection, but when set, it should be reachable.

A proxy server is an intermediary server used for caching and anonimity, often used in corporate environments. In the early days of the Internet they served to speed up dialup phone connections for home users so that cached content would be offered to customers if possible, avoiding new network retrieval and additional delay, also saving bandwidth for ISP’s. Nowadays they’re less useful and often "transparent" for home users anyway, i.e. they don’t really anonymize and can even slow down connections. Moreover, most proxy servers serve for web content only and not for email, hence perhaps an email containing a remote image, the What’s new page or the Add-on page may have triggered the issue for you.

Thunderbird and Firefox use the system proxy settings (or rather, its network settings) by default for new setups, relying on the fact they are fine and often required for some environments, so they should be set up properly, unless they’re ignored by applications (often offering separate network settings.) These system settings are in Control Panel > Internet Options (also accessible in IE) > Connections > LAN Settings in Windows 7. Not entering a proxy and/or unticking any options in there as well as reverting the change in Thunderbird should give similar results now, as the system proxy/connection settings would be set to "direct".

For reference: it may be good to know that "Auto-detect proxy settings for this network" is also capable of causing the error (according to reports mentioned in bug 926022.) I’m not sure but assume that also goes for the similar auto-detection option in Windows connection settings.

In general, a Thunderbird update should not modify this type of user settings in Thunderbird, though an update can add preferences for a new feature. On the other hand, if you are absolutely sure nothing else was changed recently and hence the recent Thunderbird update caused it, some recent network related code change may be involved. Therefor, could you tell what Thunderbird version you updated from? If you can’t remember, Thunderbird’s update history can be viewed in Options > Advanced > Update tab > Show Update Log. That might help developers tracing back any network related code changes triggering the issue if it gets reported more often, i.e. they’d probably like to know if it started somewhere between 38.x and 45.4 (in case you didn’t update TB for a while), or between e.g. 45.3 and 45.4.

If you disabled the warning by clicking Don’t show again and like to restore them for this type of error, do this:

1. Open the Config Editor using Options > Advanced > General tab > Config Editor
2. Accept the warning, and type dom.max_script_run_time or a part of it (is it set to 0?)
3. Right-click and select Reset - this should set the value back to 10
4. Close the dialogs

When left as is, that may of course lead to similar hang or other issues without showing the error message you provided, which as you see can be helpful.