I currently have V5.77.8521 CCLeaner Professional Plus installed and and the update appears to download, CCLeaner closes and the install does not process.
I currently have V5.77.8521 CCLeaner Professional Plus installed and and the update appears to download, CCLeaner closes and the install does not process.
What you describe is usually caused by your antivirus or firewall settings blocking the install.
Try downloading the Slim installer 'ccsetup578_slim.exe' from the builds page:
https://www.ccleaner.com/ccleaner/builds
Once downloaded double click it to install.
(If it still doesn't install then try disconnecting from the internet and then double clicking it again. Note that if that works it indicates that something AV/firewall is blocking it and may also block some of the standard CCleaner tools/options).