diff --git a/cmd/helper/error.go b/cmd/helper/error.go
index ff9f84af6c..aafd30088f 100644
--- a/cmd/helper/error.go
+++ b/cmd/helper/error.go
@@ -25,10 +25,12 @@ import (
 	"google.golang.org/grpc/status"
 )
 
+var osexit = os.Exit
+
 // QuitToStdErr prints an error on stderr and closes
 func QuitToStdErr(msg interface{}) {
 	_, _ = fmt.Fprintln(os.Stderr, msg)
-	os.Exit(1)
+	osexit(1)
 }
 
 // QuitWithUserError ...
@@ -42,3 +44,7 @@ func QuitWithUserError(err error) {
 	}
 	QuitToStdErr(err)
 }
+
+func OverrideQuitter(quitter func(int)) {
+	osexit=quitter
+}
diff --git a/cmd/immudb/command/cmd_test.go b/cmd/immudb/command/cmd_test.go
index 9b67a67087..ae9e57901e 100644
--- a/cmd/immudb/command/cmd_test.go
+++ b/cmd/immudb/command/cmd_test.go
@@ -28,6 +28,7 @@ import (
 	"github.com/spf13/cobra"
 	"github.com/spf13/viper"
 	"github.com/stretchr/testify/assert"
+	"github.com/codenotary/immudb/cmd/helper"
 )
 
 func DefaultTestOptions() (o *server.Options) {
@@ -66,6 +67,37 @@ func TestImmudbCommandFlagParser(t *testing.T) {
 	assert.Equal(t, o.Logfile, options.Logfile)
 }
 
+func TestImmudbCommandFlagParserWrongTLS(t *testing.T) {
+	viper.Set("mtls", true)
+	o := DefaultTestOptions()
+
+	var err error
+	cmd := &cobra.Command{
+		Use: "immudb",
+		RunE: func(cmd *cobra.Command, args []string) (err error) {
+			_, err = parseOptions()
+			if err != nil {
+				return err
+			}
+			return nil
+		},
+	}
+	cl := Commandline{}
+	cl.setupFlags(cmd, server.DefaultOptions())
+
+	err = viper.BindPFlags(cmd.Flags())
+	assert.Nil(t, err)
+
+	setupDefaults(server.DefaultOptions())
+
+	_, err = executeCommand(cmd, "--logfile="+o.Logfile)
+
+	assert.Error(t, err)
+	viper.Set("mtls", false)
+}
+
+
+
 //Priority:
 // 1. overrides
 // 2. flags
@@ -210,3 +242,13 @@ func TestNewCommand(t *testing.T) {
 	_, err := newCommand(server.DefaultServer())
 	require.NoError(t, err)
 }
+
+func TestExecute(t * testing.T) {
+	quitCode := 0
+	os.Setenv("IMMUDB_ADDRESS","999.999.999.999")
+	helper.OverrideQuitter(func(q int) {
+		quitCode=q
+	})
+	Execute()
+	assert.Equal(t, quitCode,1)
+}
diff --git a/cmd/immudb/command/tls_config_test.go b/cmd/immudb/command/tls_config_test.go
new file mode 100644
index 0000000000..3679613125
--- /dev/null
+++ b/cmd/immudb/command/tls_config_test.go
@@ -0,0 +1,75 @@
+/*
+Copyright 2021 CodeNotary, Inc. All rights reserved.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+	http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package immudb
+
+import (
+	"fmt"
+	"github.com/stretchr/testify/require"
+	"os"
+	"testing"
+)
+
+var key = `
+-----BEGIN PRIVATE KEY-----
+MIIBVAIBADANBgkqhkiG9w0BAQEFAASCAT4wggE6AgEAAkEApIGvkc3ROIC18zdL
+K3I4VhKmY7gq1YU53dIwikrd5uy/fjUTmW73rLlthkV1zPvG/34rsW9kMDanmndb
+QENmHwIDAQABAkEAkOW9vCJaP3d3TCQO7NStdHr23eywpeO0BYMGyDiLXcMOcjaT
+MrkeCMyXsgtIaoh/sPFO356z2DXjz8Z4PY53EQIhANPSp0dOKi4OeqHdSsj8wjwt
+eeAxCcASe3cz18gnBUB5AiEAxtDJ3spTLNogOoOzQA8g7rVT8xW5R5xQwfmvZwQx
+JVcCICAIkGGZMYnLiMInzCJ/DwS4v+CmqdnRMbjCL1TGieXJAiBvQXNWCx6UYNPc
+KsrqNA0Xx7zcsPFn01+VzOWM3lmqLQIgdUukJDJHjdX203wOJMd51jq3I+c1n09A
+SXr+Ea7CjsE=
+-----END PRIVATE KEY-----
+`
+
+var cert = `
+-----BEGIN CERTIFICATE-----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+-----END CERTIFICATE-----
+`
+
+func TestSetUpTLS(t *testing.T) {
+	_, err := setUpTLS("banana", "banana", "banana", false)
+	require.Error(t, err)
+	_, err = setUpTLS("", "", "", true)
+	require.Error(t, err)
+	_, err = setUpTLS("banana", "", "", true)
+	require.Error(t, err)
+
+	defer os.Remove("xxkey.pem")
+	f, _ := os.Create("xxkey.pem")
+	fmt.Fprintf(f, key)
+	f.Close()
+
+	defer os.Remove("xxcert.pem")
+	f, _ = os.Create("xxcert.pem")
+	fmt.Fprintf(f, cert)
+	f.Close()
+
+	_, err = setUpTLS("xxkey.pem", "xxcert.pem", "banana", true)
+	require.Error(t, err)
+}
diff --git a/embedded/ahtree/ahtree_test.go b/embedded/ahtree/ahtree_test.go
index d9b01d4763..7a0a6efa89 100644
--- a/embedded/ahtree/ahtree_test.go
+++ b/embedded/ahtree/ahtree_test.go
@@ -23,6 +23,7 @@ import (
 
 	"github.com/codenotary/immudb/embedded/appendable"
 	"github.com/codenotary/immudb/embedded/appendable/mocked"
+	"github.com/codenotary/immudb/embedded/appendable/multiapp"
 
 	"github.com/stretchr/testify/require"
 )
@@ -340,6 +341,33 @@ func TestIntegrity(t *testing.T) {
 	}
 }
 
+func TestOpenFail(t *testing.T) {
+	_, err := Open("/dev/null", DefaultOptions().WithSynced(false))
+	require.Error(t, err)
+	os.Mkdir("ro_dir1", 0500)
+	defer os.RemoveAll("ro_dir1")
+	_, err = Open("ro_dir/bla", DefaultOptions().WithSynced(false))
+	require.Error(t, err)
+	_, err = Open("wrongdir\000", DefaultOptions().WithSynced(false))
+	require.Error(t, err)
+	defer os.RemoveAll("tt1")
+	_, err = Open("tt1", DefaultOptions().WithSynced(false).WithAppFactory(
+			func (rootPath, subPath string, opts *multiapp.Options) (a appendable.Appendable, e error) {
+				if subPath=="tree" {
+					e = errors.New("simulated error")
+				}
+				return
+			} ))
+	_, err = Open("tt1", DefaultOptions().WithSynced(false).WithAppFactory(
+			func (rootPath, subPath string, opts *multiapp.Options) (a appendable.Appendable, e error) {
+				if subPath=="commit" {
+					e = errors.New("simulated error")
+				}
+				return
+			} ))
+	require.Error(t, err)
+}
+
 func TestInclusionAndConsistencyProofs(t *testing.T) {
 	tree, err := Open("ahtree_test", DefaultOptions().WithSynced(false))
 	require.NoError(t, err)
diff --git a/embedded/store/indexer_test.go b/embedded/store/indexer_test.go
index c071b5a7a5..8efd8c40f0 100644
--- a/embedded/store/indexer_test.go
+++ b/embedded/store/indexer_test.go
@@ -24,6 +24,7 @@ import (
 
 	"github.com/codenotary/immudb/embedded/tbtree"
 	"github.com/codenotary/immudb/embedded/watchers"
+	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
 )
 
@@ -174,5 +175,38 @@ func TestReplaceIndexCornerCases(t *testing.T) {
 			c.fn(t, d, store)
 		})
 	}
+}
+
+func TestClosedIndexer(t *testing.T) {
+	i := indexer{closed: true}
+	var err error
+	dummy := []byte("dummy")
+
+	_, _, _, err = i.Get(dummy)
+	assert.Error(t, err)
+	assert.Equal(t, err, ErrAlreadyClosed)
+
+	_, err = i.History(dummy, 0, false, 0)
+	assert.Error(t, err)
+	assert.Equal(t, err, ErrAlreadyClosed)
+
+	_, err = i.Snapshot()
+	assert.Error(t, err)
+	assert.Equal(t, err, ErrAlreadyClosed)
+
+	_, err = i.SnapshotSince(0)
+	assert.Error(t, err)
+	assert.Equal(t, err, ErrAlreadyClosed)
+
+	_, err = i.ExistKeyWith(dummy, dummy, false)
+	assert.Error(t, err)
+	assert.Equal(t, err, ErrAlreadyClosed)
+
+	err = i.Sync()
+	assert.Error(t, err)
+	assert.Equal(t, err, ErrAlreadyClosed)
 
+	err = i.Close()
+	assert.Error(t, err)
+	assert.Equal(t, err, ErrAlreadyClosed)
 }
diff --git a/pkg/client/sql_test.go b/pkg/client/sql_test.go
index d02b6a7826..0d60206af0 100644
--- a/pkg/client/sql_test.go
+++ b/pkg/client/sql_test.go
@@ -29,6 +29,24 @@ import (
 	"google.golang.org/grpc/metadata"
 )
 
+func TestDisconnectedImmuClient(t *testing.T) {
+	options := server.DefaultOptions().WithAuth(true)
+	bs := servertest.NewBufconnServer(options)
+
+	defer os.RemoveAll(options.Dir)
+	defer os.Remove(".state-")
+
+	bs.Start()
+	defer bs.Stop()
+
+	client, err := NewImmuClient(DefaultOptions().WithDialOptions(&[]grpc.DialOption{grpc.WithContextDialer(bs.Dialer), grpc.WithInsecure()}))
+	client.Disconnect()
+	_,err = client.SQLExec(context.Background(), "SELECT 1", nil)
+	require.Error(t, err)
+	_,err = client.SQLQuery(context.Background(), "SELECT 1", nil, true)
+	require.Error(t, err)
+}
+
 func TestImmuClient_SQL(t *testing.T) {
 	options := server.DefaultOptions().WithAuth(true)
 	bs := servertest.NewBufconnServer(options)
@@ -48,10 +66,10 @@ func TestImmuClient_SQL(t *testing.T) {
 	ctx := metadata.NewOutgoingContext(context.Background(), md)
 
 	_, err = client.SQLExec(ctx, `CREATE TABLE table1(
-		id INTEGER, 
-		title VARCHAR, 
-		active BOOLEAN, 
-		payload BLOB, 
+		id INTEGER,
+		title VARCHAR,
+		active BOOLEAN,
+		payload BLOB,
 		PRIMARY KEY id
 		);`, nil)
 	require.NoError(t, err)