DA: can't open the log file to write

After start DA, after some time DA log to /var/log/directadmin/error.log:

2018:06:12-13:06:50: can't open the log file to write
2018:06:12-13:07:48: can't open the log file to write
2018:06:12-13:07:57: can't open the log file to write
2018:06:12-13:08:03: can't open the log file to write
2018:06:12-13:08:27: can't open the log file to write

How debug which log file can't be open?

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