Derby is still in read-only mode，even through I had released the disk space, and can't update data in database

I cleaned up disk and there are 80% of disk is freed for derby. But the derby is still in read-only mode:
java.sql.SQLException: An SQL data change is not permitted for a read-only connection, user or database.
org.apache.derby.impl.jdbc.EmbedSQLException: An SQL data change is not permitted for a read-only connection, user or database.
org.apache.derby.iapi.error.StandardException: An SQL data change is not permitted for a read-only connection, user or database.

Caused by: java.io.IOException: No space left on device
at java.io.RandomAccessFile.writeBytes0(Native Method)
at java.io.RandomAccessFile.writeBytes(RandomAccessFile.java:520)
at java.io.RandomAccessFile.write(RandomAccessFile.java:550)
at org.apache.derby.impl.store.raw.log.LogAccessFile.writeToLog(Unknown Source)
at org.apache.derby.impl.store.raw.log.LogAccessFile.flushDirtyBuffers(Unknown Source)
... 23 more