Hi @Nora Lahlouh ,
According to your description, do you mean you are trying to upgrade to Exchange 2010 SP3 but the prerequistes check fails due to the two missed files listed?
What's the version of your current Exchange server?
I tried searching around and also noticed that the download for these two files are no longer available in Microsoft sites. According to the discussion in this link which is about "Microsoft Unified Communications Managed API 2.0 Core Runtime", seems that it could be related to the end of support for Exchange Server 2010.
Given this situaiton, instead of searching for the old files to upgrade on the current Exchange server, personally I'd recommend trying to introduce a new Exchange 2010 SP3 into your current environment after preparing AD and domains, then you can move all mailboxes to the new Exchange 2010 SP3 and decommssion the old Exchange server afterwards.
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