Cause: Corrupt download or antivirus interference.
Fix: Disable Windows Defender/third-party AV temporarily. Delete the downloaded .exe, re-download, and try again.
Cause: You have CSP EX active on two previous devices you no longer use. Solution:
💡 For the free trial, skip serial entry – it will automatically start the trial period after login.
CELSYS allows activation on two devices per license for the same OS family (e.g., two Windows PCs). If you exceed this, the install will fail. Before installing EX on a new computer, open CSP on your old machine and go to: Help menu > Review/Change License > Deactivate.
Mac users often struggle with Gatekeeper blocking the installer. Here is the safe method.
