The issue is that the Exchange install looks at certain registry keys and if it finds a value, it reports this issue.
The most common registry key is the PendingFileRenameOperations key which can be found at the below location:
To resolve the issue, open up regedit, browse to the location and delete the value for the key. Double click on PendingFileRenameOperations on the right, delete the value then click ok.
Once you've done this, you can continue the install of Exchange, however, you may find that it still fails. In this case, you should look for the next registry key which is the UpdateExeVolatile key and can be found in the path below:
This key needs to either be set to a value of 0 or deleted.
More information can be found here: https://technet.microsoft.com/en-us/library/cc164360%28v=exchg.80%29.aspx