Network error 0x2ef3 KeepAliveTimeout

Problem

Although unblu works with all current and popular browsers on the market, there can sometimes be problems specific to the combination of application server/browser/configuration that are out of unblu's control.

Such a problem can occur when using Microsoft Internet Explorer or Microsoft Edge with a web server. Note that here, for the sake of clarity, we use the example combination of a Microsoft browser and an Apache server. But while this seems to be the most common setup where this issue is reproduced be aware that it can happen with any modern web server communicating with a Microsoft browser. Also note that, at time of writing, Microsoft has closed the issue as they are apparently unable to reproduce it. This means that you must take action to fix the issue.

The default 'keep-alive' timeout interval for Apache Tomcat is 20 seconds. The default for Apache httpd is only 5 seconds. In order to ensure optimal performance this value must be increased to at least 75 seconds.

Most modern application servers have a timeout value either equal to or greater than 75 seconds (or a more sophisticated way of handling requests where the timeout is either longer or shorter according to load).

Note that this problem generates the following error code: "Network Error 0x2ef3, Could not complete the operation due to error 00002ef3."

Solution

Apache Web Server / Internet Explorer 'Keep-Alive' setting

If you use an Apache web server with Internet Explorer you must increase the Default HTTP persistent connection idle timeout value to ≥ 75s. Failure to do so may cause a timeout. You may choose to do this using one of the following methods.

  1. Configure the involved HTTP infrastructure (including the application server, proxies, firewall and load balancer) to have KeepAliveTimeout set to 75 seconds.

  2. Configure the involved HTTP infrastructure (including the application server, proxies, firewall and load balancer) to have KeepAliveTimeout set to 75 seconds depending on the user agent (only for Internet Explorer).

  3. Configure the involved HTTP infrastructure (including the application server, proxies, firewall and load balancer) to selectively turn off KeepAlive for Internet Explorer.

  4. Set unblu heartbeat to 1 second. (com.unblu.nio.heartbeatInterval=1)

Caution: If workaround 4 is chosen: This MUST be removed if you move to 4.2.x, or above. We recommend using one of the first three solutions, if possible.

Custom Proxies

If you have your own proxy setup in Apache, make sure that it is a non-caching reverse proxy that does not deliver its own (cached) content. Cached content is not processed by mod_unblufilter and cannot be co-browsed.

Reverse Proxy Integration

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  • deployonprem

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