Error message when connecting to split database in Writer. Is there a problem?

I get the following error message when printing a mail merge in Writer from a split database? I seem to be able to print ok. Does anyone know the reason for the message and if it can be remedied?

Here it is:
Warnings were encountered while connecting to the data source. Press more to see them.
cursor updatability mismatch

Upon pressing “more”, I get:
SQL Status: 36502
Error code: -4712

cursor updatability mismatch

Same problem using Base. Mystified!
LO 5.1.6.2 Ubuntu 16.04

Tested with embedded, Split (using table & Query) and MySQL DB’s and no problems in any.

The message is not unique to a Split DB and is an HSQL warning. Possibly due to a Column constraint.

Without further information on specifics (source - table, query; resulting output, actual data and maybe other definitions) it is not possible to give a specific answer.

Sorry I was away so long. Now I am back. Now I cannot connect to the database to print at all. Here is what I see in the database properties box:

jdbc:hsqldb:file:////home/DATABASES/Addresses;default_schema=true;shutdown=true;hsqldb.default_table_type=cached;get_column_name=false

jdbc driver class: org.hsqldb.jdbcDriver
When I test class, I get: The Jdbc driver could not be loaded.

When I test connection I get: Error code: 1000
The driver class ‘org.hsqldb.jdbcDriver’ could not be loaded

Your comment isn’t clear. Does the Base file itself work? Can you view tables & forms? The JDBC error can be ignored. This is always true in the split DB. Are you just saying you can’t connect to DB from Writer? If so, is the DB registered?

Yes the base file works and I can view tables and forms and even print a report from Base. But as I was using a split database with macros included, I have since copied the one table I want to use data from into an embedded database, exchanged the database and am able to connect.
Now I am wondering if the split database didn’t work because there is no jdbc driver org.hsqldb.jdbcDriver . When I look at the Options LibreOfficeBase - Connections among the drivers known in LO, I find no jdbc

Sorry, but I really don’t get your last comment. First you say the Base file works. What is this copy? Exchanged database - haven’t a clue here? Then you say the split didn’t work - but you opened by saying it works??? As stated in my previous comment, the JDBC error can be ignored. It happens on ALL split DB’s.

When I attempt a mail merge in LIBREOFFICE WRITER there is no connection. In writer under the edit menu there is a menu item: Exchange Database. Thus I exchanged the link to my split-database to the new embedded one. It worked.
However, I have managed since to get the split db to work also. It may simply have been a problem in the location/path of the split db which somehow was lost over time. Thank you for forcing me to probe into this in this direction and thus resolve my problem.

Well I’m just glad you got things to work. Sorry, I was confused but in the future please try to be a little more specific. Your last comment was a good example of specifics.