diff --git a/copy_from_test.go b/copy_from_test.go
index 9da23c04f..423337e45 100644
--- a/copy_from_test.go
+++ b/copy_from_test.go
@@ -803,6 +803,40 @@ func TestConnCopyFromAutomaticStringConversion(t *testing.T) {
 	ensureConnValid(t, conn)
 }
 
+// https://github.com/jackc/pgx/discussions/1891
+func TestConnCopyFromAutomaticStringConversionArray(t *testing.T) {
+	t.Parallel()
+
+	ctx, cancel := context.WithTimeout(context.Background(), 120*time.Second)
+	defer cancel()
+
+	conn := mustConnectString(t, os.Getenv("PGX_TEST_DATABASE"))
+	defer closeConn(t, conn)
+
+	mustExec(t, conn, `create temporary table foo(
+		a numeric[]
+	)`)
+
+	inputRows := [][]interface{}{
+		{[]string{"42"}},
+		{[]string{"7"}},
+		{[]string{"8", "9"}},
+		{[][]string{{"10", "11"}, {"12", "13"}}},
+	}
+
+	copyCount, err := conn.CopyFrom(ctx, pgx.Identifier{"foo"}, []string{"a"}, pgx.CopyFromRows(inputRows))
+	require.NoError(t, err)
+	require.EqualValues(t, len(inputRows), copyCount)
+
+	// Test reads as int64 and flattened array for simplicity.
+	rows, _ := conn.Query(ctx, "select * from foo")
+	nums, err := pgx.CollectRows(rows, pgx.RowTo[[]int64])
+	require.NoError(t, err)
+	require.Equal(t, [][]int64{{42}, {7}, {8, 9}, {10, 11, 12, 13}}, nums)
+
+	ensureConnValid(t, conn)
+}
+
 func TestCopyFromFunc(t *testing.T) {
 	t.Parallel()
 
diff --git a/values.go b/values.go
index 19c642fa9..cab717d0a 100644
--- a/values.go
+++ b/values.go
@@ -55,7 +55,11 @@ func encodeCopyValue(m *pgtype.Map, buf []byte, oid uint32, arg any) ([]byte, er
 func tryScanStringCopyValueThenEncode(m *pgtype.Map, buf []byte, oid uint32, arg any) ([]byte, error) {
 	s, ok := arg.(string)
 	if !ok {
-		return nil, errors.New("not a string")
+		textBuf, err := m.Encode(oid, TextFormatCode, arg, nil)
+		if err != nil {
+			return nil, errors.New("not a string and cannot be encoded as text")
+		}
+		s = string(textBuf)
 	}
 
 	var v any