@book{test_123,
        title = {How to use { in Bib(La)TeX?}
}

INFO - This is Biber 1.9 running in TOOL mode
INFO - Logfile is 'test.bib.blg'
INFO - Looking for bibtex format file 'test.bib'
INFO - Decoding LaTeX character macros into UTF-8
INFO - Found BibTeX data source 'test.bib'
WARN - Entry test_123 does not parse correctly
WARN - BibTeX subsystem: C:*********test.bib_5644.utf8, line 3, warning: possible runaway string started at line 2
ERROR - BibTeX subsystem: C:********test.bib_5644.utf8, line 4, syntax error: at end of input, expected one of: number, name (entry type, key, field, or macro name) or quoted string ({...} or "...")
INFO - WARNINGS: 2
INFO - ERRORS: 1