Unable to connect to Base database

When I try to connect to my Base database (LO v running on Mac I get the following message :
" The connection to the data source < my db name > could not be established.
File input/output error
The stream seems to be broken ! "

SQL Status S1000
Error code -29

Earlier I had successfully input data, run a couple of queries and logged off cleanly. The last session contained no untoward problems so I am at a loss to understand what the problem might be.
Could someone please advise . Many Thanks