I'm attempting to set IIS up as a 'front end' for Tomcat but have run into a frustrating issue. I can't seem to get the Tomcat connector to recognize when it should be handling the appropriate requests. The isapi_redirect.dll seems to be getting initialized successfully according to the log file, but that's as far as it goes:

[Thu Dec 05 13:00:14.811 2019] [2148:5332] [info] init_jk::jk_isapi_plugin.c (2490): Starting Tomcat/ISAPI/isapi_redirector/1.2.46
[Thu Dec 05 13:00:14.811 2019] [2148:5332] [info] init_jk::jk_isapi_plugin.c (2687): Tomcat/ISAPI/isapi_redirector/1.2.46 initialized

I'm also not seeing this in the IIS log file GET "/jakarta/isapi_redirect.dll HTTP1.1 which seems to further indicate the redirector doesn't recognize that it should handle the request.

I know Tomcat itself is working because I can browse to 'localhost:8080/examples' which contains some sample Java Servlets to run under Tomcat. However, when I navigate to 'localhost/examples' which should be forwarded from IIS to Tomcat, I get an HTTP 404 error. I've trawled forum post after forum post looking for clues and insights but have come up empty handed so far.

I am currently running Windows Server 2016 on a virtual machine and have IIS 10 and Apache 8.5.49 installed (previously tried Apache 9.0.29). I'm also using version 1.2.46 of the isapi_redirect.dll. I've explicitly followed the how-to guide here: Apache ISAPI connector how-to

I'm beginning to wonder if this issue is related to IIS 10 itself.

Does anyone have any suggestions? If I've omitted any information that would be helpful, please let me know and I can provide it.


  • Duplicate to serverfault.com/questions/952154/… and you should dump that buggy ISAPI. – Lex Li Dec 5 '19 at 19:07
  • Thanks for the info. What would be your recommendation with respect to what I would dump ISAPI in favor of? Also, it's good to hear ISAPI described as 'buggy' - makes me feel like not as much of an idiot for not being able to get it to work. – CacheMoney Dec 5 '19 at 19:49
  • I've attempted to bypass the Tomcat connector by using HttpPlatformHandler and I'm still having issues. I followed the steps in the article listed below to the letter (including matching SW versions) and when I navigate to localhost in my browser, the browser sits indefinitely trying to load the page. No Tomcat welcome page, no 404, no timeout, no nothing. Any ideas? Tomcat via HttpPlatformHandler – CacheMoney Dec 9 '19 at 14:34
  • EDIT to my most recent comment. I noticed an error in my web.config file and corrected it. Now I am getting a 404 error when attempting to connect to localhost. – CacheMoney Dec 9 '19 at 14:54
  • You might assume this resolved the issue, but from time to time that ISAPI will give you headaches. Good luck. – Lex Li Dec 9 '19 at 16:26

I seem to have figured this out after a lot of digging in the tomcat log files. Apparently step 6A in the tutorial I linked to above breaks Tomcat. I changed "Connector port=”${port.http}" to "Connector port=”8080" and it started working.

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