This cropped up while doing some tests...
Start Gnucash with --nofile, take all default options and when saving use
sqlite3 option and appropriate file name, close Gnucash.
Start Gnucash again with --nofile, again take all default options and when
saving use sqlite3 again with the same file name, dialogue appears asking
if you want to overwrite, say yes and then this dialogue appears..

"The server URL at /root/unstable-sql3-1.gnucash experienced an error or
encountered bad or corrupt data", close

In the trace file entries like these are present...

* 13:30:11  CRIT <gnc.engine.sx> gnc_sx_get_sxes_referencing_account:
assertion 'sxactions != NULL' failed
* 13:30:21  WARN <gnc.backend.dbi> [GncDbiBackend<Type>::session_begin()]
Might clobber, no force
* 13:30:24  CRIT <gnc.backend.dbi> [error_handler()] DBI error: 1: table
versions already exists
* 13:30:24  CRIT <gnc.backend.dbi> [GncDbiSqlConnection::create_table()]
Error in dbi_result_free() result
* 13:30:24  CRIT <gnc.backend.dbi> [error_handler()] DBI error: 19: UNIQUE
constraint failed: versions.table_name
* 13:30:24  CRIT <gnc.backend.dbi>
[GncDbiSqlConnection::execute_nonselect_statement()] Error executing SQL
INSERT INTO versions VALUES('Gnucash',2070000)
* 13:30:24  CRIT <gnc.backend.sql>
[GncSqlBackend::execute_nonselect_statement()] SQL error: INSERT INTO
versions VALUES('Gnucash',2070000)
* 13:30:24  CRIT <gnc.backend.sql> [GncSqlBackend::set_table_version()] SQL
error: INSERT INTO versions VALUES('Gnucash',2070000)
* 13:30:24  CRIT <gnc.backend.dbi> [error_handler()] DBI error: 19: UNIQUE
constraint failed: versions.table_name
* 13:30:24  CRIT <gnc.backend.dbi>
[GncDbiSqlConnection::execute_nonselect_statement()] Error executing SQL
INSERT INTO versions VALUES('Gnucash-Resave',19920)