This happens when the EPIM database you’re trying to connect to is already opened locally (by using File->Open command) on the server. All EPIM clients should always open databases on the server via "File -> Connect to a server" even if you’re on the same PC (server) the file is stored on.
EssentialPIM tells me that that database is already in use by another app when I try to connect to it.
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What does database open locally mean?
What does "Connect to a server mean"?
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