Lucas, did these failed extracts work before? From the error message it appears that your Tableau Server is trying to connect to a file on your PCs local drive, and it will not be able to do it (unless the Tableau Server is set up on your PC or your local drive is shared on the network).
If a workbook uses extracts, the server needs to be able to access the source from which these extracts were made, so that it can refresh them.
You can also extract the data on your local PC (i.e. connect to an existing extract) and push it to the Server via "include external files" publishing option, but then there will be no way of refreshing it, which seems to be the case in your situation.
I am also facing the same problem that Lucas has mentioned. I am using Tableau 7.0.13.
I have Tableau Desktop and Server are on the same machine. I am able to publish the same workbook using Desktop but getting error while publishing via tabcmd. Following is the error snapshot:
C:\Program Files (x86)\Tableau\Tableau Server\7.0\bin>tabcmd publish "C:\Users\nitin.agarwal\Documents\My Tableau Repository\Workbooks\Book2.twb" -s "http://localhost" -u "abc" -p "xyz" -n "Book2_via_tabcmd" -r "Test Project" --db-username "dbuser" --db-password "xyz" --save-db-password
===== Continuing previous session
===== Server: http://localhost/
===== Username: abc
===== Connecting to server...
===== Publishing C:\Users\nitin.agarwal\Documents\My Tableau Repository\Workbooks\Book2.twb to server. This could take several minutes...
*** Tableau Server encountered an internal error.
com.tableausoftware.vizql.dll.TableauException: Tableau Data Engine Error: 4: Invalid Command: database: Path does not exist.
Unable to connect to the file "C:\Users\nitin.agarwal\Documents\My Tableau Repository\Datasources\test.tde". Check that the file exists and that you have sufficient access privileges for it.
Errors occurred while trying to load the workbook "". The load was not able to complete successfully.