The .msi installer denies to run if a previous version is installed. It's extremely bad behaviour, it barres me from doing any elaborate side-by-side install on productions systems. I've used an NTFSlink ("Windows symlink") which would allow to switch between different versions even w/o re-installing the service nor system reboot. And its also more or less dumb behaviour, since the only thing to consider on a default install would have been checking whether port 80 is in use (for that purpose, MS offers a tiny free tool named "portqry", AFAIK) and incrementing port number and service name, if yes. Surely your intention was thrashing a bit at the dumb user only.
Please help us to refine our list of open and current defects; this is a mass update of old and inactive Bugzilla reports which reflect user error, already resolved defects, and still-existing defects in httpd. As repeatedly announced, the Apache HTTP Server Project has discontinued all development and patch review of the 2.2.x series of releases. The final release 2.2.34 was published in July 2017, and no further evaluation of bug reports or security risks will be considered or published for 2.2.x releases. All reports older than 2.4.x have been updated to status RESOLVED/LATER; no further action is expected unless the report still applies to a current version of httpd. If your report represented a question or confusion about how to use an httpd feature, an unexpected server behavior, problems building or installing httpd, or working with an external component (a third party module, browser etc.) we ask you to start by bringing your question to the User Support and Discussion mailing list, see [https://httpd.apache.org/lists.html#http-users] for details. Include a link to this Bugzilla report for completeness with your question. If your report was clearly a defect in httpd or a feature request, we ask that you retest using a modern httpd release (2.4.33 or later) released in the past year. If it can be reproduced, please reopen this bug and change the Version field above to the httpd version you have reconfirmed with. Your help in identifying defects or enhancements still applicable to the current httpd server software release is greatly appreciated.