Refused To Install Updates

I have this notification to install updates on CCleaner 5.50.6911, and everytime I clicked update, it downloaded something, then automatically installed.. and then stopped. I tried to clean registry, run ccleaner before installing, and then it kept happening. What happened?

ccleaner.jpg

See here

https://forum.piriform.com/topic/53111-fail-to-install-ccleaner-pro-v5516939/?tab=comments#comment-302097

Quote
<div class="ipsQuote_contents">
	<p>
		<span style="background-color:#ffffff;color:#353c41;font-size:14px;">This warning is usually accompanied by ccleaner still running.  Make sure ccleaner is fully exited including smart clean monitoring.  Check task manager for ccleaner.exe or ccleaner64.exe. Kill those instances then manully delete the file c:\program files\ccleaner\ccleaner.exe (or the file listed in the error message).  Finally click retry</span>
	</p>
</div>

It's really strange that Piriform still hasn't fixed the installer. The installer could run a simple command before copying the new files:

TASKKILL /F /FI "IMAGENAME eq CCleaner*"

I thought the same, it's been too long for that to still exist.