UltraLite Embedded SQL User's Guide
Synchronization Parameters Reference
Synchronization parameters
Disallow database access from other threads during synchronization.
By default, data access is available. Data access is read-write during the download phase, and read-only otherwise.
Set the parameter as follows:
ul_synch_info info; // ... info.disable_concurrency = ul_false ;
Threading in UltraLite applications