Many people, starting with myself, often skip reading all the documentation before upgrading a product. More often than not the release notes are not meaningful so they skip directly to the installation procedure.
For Connections 4.5 CF1 is not the case. In the release notes section of this document is stated very clearly the following "IBM Connections 4.5 environments using Connections Content Management
(CCM) must upgrade the FileNet installation to 5.2.0 fixpack 1 (FP1).
The FileNet fixpack must be applied first. After the FileNet fixpack is
successfully applied, 4.5 CR1 should then be applied."
So, if you plan an upgrade of Connections to CR1, read the above mentioned document thoroughly.