Problem

Since H2 2.3.239 (master, self-built), the command:

SHUTDOWN COMPACT;

always ends with:

org.h2.jdbc.JdbcSQLNonTransientConnectionException: Database is already closed [90121-239]

The database file size never shrinks and no .tempFile is created.

With H2 2.2.224 the same command works and the .mv.db file becomes smaller.

Steps to Reproduce

1. Build from latest master:
   ./mvnw clean package -P assembly -DskipTests
   → h2-2.3.239-SNAPSHOT.jar
2. Start H2 Shell and connect:
   java -cp h2-2.3.239-SNAPSHOT.jar org.h2.tools.Shell -url "jdbc:h2:file:./testdb"
3. Insert and delete rows.
4. Run:
   SHUTDOWN COMPACT;

Expected

Database file is compacted and shrinks.

Actual

Immediate "Database is already closed [90121-239]" error, file size unchanged.

Environment

• H2 version: 2.3.239-SNAPSHOT (self-built from master)
• Java: Corretto 11
• OS: Windows 11 x64