Error "database is locked" in wal mode

[Yanyun Tao]

In WAL mode, one transaction continues to write to the SQLite database, and another transaction will report the error "database is locked" when creating, updating, and inserting data. Is this a WAL mode configuration problem?

[Fredrik Ehnbom]

WAL doesn't allow concurrent writes. See section 2.2 concurrency, middle paragraph:

However, since there is only one WAL file, there can only be one writer at a time.