diff --git a/pyproject.toml b/pyproject.toml
index 201f5ac..3ad249d 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -4,7 +4,7 @@ build-backend = "setuptools.build_meta"
 
 [project]
 name = "rda_python_common"
-version = "3.0.0"
+version = "3.0.1"
 authors = [
   { name="Zaihua Ji", email="zji@ucar.edu" },
 ]
diff --git a/src/rda_python_common/PgDBI.py b/src/rda_python_common/PgDBI.py
index e83a819..00f9597 100644
--- a/src/rda_python_common/PgDBI.py
+++ b/src/rda_python_common/PgDBI.py
@@ -328,8 +328,12 @@ def starttran():
       pgconnect(0, 0, False)
    else:
       try:
-         pgdb.isolation_level
-      except PgSQL.OperationalError as e:
+         # Liveness probe: psycopg2's isolation_level getter could raise on a
+         # dead connection, but psycopg3's is a cached attribute that never
+         # touches the server.  A trivial round-trip detects a broken
+         # connection under either driver.
+         pgdb.cursor().execute("SELECT 1")
+      except PgSQL.Error as e:
          pgconnect(0, 0, False)
       if pgdb.closed:
          pgconnect(0, 0, False)
diff --git a/src/rda_python_common/pg_dbi.py b/src/rda_python_common/pg_dbi.py
index 4858e8d..5880c27 100644
--- a/src/rda_python_common/pg_dbi.py
+++ b/src/rda_python_common/pg_dbi.py
@@ -410,8 +410,12 @@ def starttran(self):
          self.pgconnect(0, 0, False)
       else:
          try:
-            self.pgdb.isolation_level
-         except PgSQL.OperationalError as e:
+            # Liveness probe: psycopg2's isolation_level getter could raise on a
+            # dead connection, but psycopg3's is a cached attribute that never
+            # touches the server.  A trivial round-trip detects a broken
+            # connection under either driver.
+            self.pgdb.cursor().execute("SELECT 1")
+         except PgSQL.Error as e:
             self.pgconnect(0, 0, False)
          if self.pgdb.closed:
             self.pgconnect(0, 0, False)
@@ -533,7 +537,11 @@ def try_add_table(self, dberror, logact):
          dberror (str): Full database error string to inspect.
          logact (int): Logging action flags forwarded to add_new_table().
       """
-      ms = re.match(r'^42P01 ERROR:  relation "(.+)" does not exist', dberror)
+      # The caller (check_dberror) only invokes this after pgcode == '42P01', so
+      # match just the relation message.  psycopg2's pgerror includes the
+      # 'ERROR:  ' severity prefix while psycopg3's message_primary does not, so
+      # anchoring on that prefix only matched under psycopg2.
+      ms = re.search(r'relation "(.+)" does not exist', dberror)
       if ms:
          tname = ms.group(1)
          self.add_new_table(tname, logact = logact)