diff --git a/.travis.yml b/.travis.yml
index 099f91188..8d00edf27 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -1,7 +1,7 @@
 language: go
 
 go:
-  - 1.14
+  - 1.15
 
 script: go test -v ./...
 
diff --git a/go.mod b/go.mod
index ced846064..bd0fca4fb 100644
--- a/go.mod
+++ b/go.mod
@@ -1,6 +1,6 @@
 module github.com/cgrates/cgrates
 
-go 1.14
+go 1.15
 
 // replace github.com/cgrates/radigo => /home/dan/go/src/github.com/cgrates/radigo
 // replace github.com/cgrates/rpcclient => ../rpcclient
diff --git a/utils/apitpdata_test.go b/utils/apitpdata_test.go
index 13d34e21d..fc06add02 100644
--- a/utils/apitpdata_test.go
+++ b/utils/apitpdata_test.go
@@ -111,7 +111,7 @@ func TestNewRateSlot(t *testing.T) {
 	eOut.RateUnit = "a"
 	rcv, err = NewRateSlot(eOut.ConnectFee, eOut.Rate, eOut.RateUnit, eOut.RateIncrement, eOut.GroupIntervalStart)
 	//must receive from time an error: "invalid duration a"
-	if err == nil || err.Error() != "time: invalid duration a" {
+	if err == nil || err.Error() != "time: invalid duration \"a\"" {
 		t.Error(err)
 	}
 }
@@ -128,19 +128,19 @@ func TestSetDurations(t *testing.T) {
 	}
 	rs.RateUnit = "a"
 	//at RateUnit if, must receive from time an error: "invalid duration a"
-	if err := rs.SetDurations(); err == nil || err.Error() != "time: invalid duration a" {
+	if err := rs.SetDurations(); err == nil || err.Error() != "time: invalid duration \"a\"" {
 		t.Error(err)
 	}
 	rs.RateUnit = "1"
 	rs.RateIncrement = "a"
 	//at RateIncrement, must receive from time an error: "invalid duration a"
-	if err := rs.SetDurations(); err == nil || err.Error() != "time: invalid duration a" {
+	if err := rs.SetDurations(); err == nil || err.Error() != "time: invalid duration \"a\"" {
 		t.Error(err)
 	}
 	rs.RateIncrement = "1"
 	rs.GroupIntervalStart = "a"
 	//at GroupIntervalStart, must receive from time an error: "invalid duration a"
-	if err := rs.SetDurations(); err == nil || err.Error() != "time: invalid duration a" {
+	if err := rs.SetDurations(); err == nil || err.Error() != "time: invalid duration \"a\"" {
 		t.Error(err)
 	}
 }
diff --git a/utils/basic_auth_test.go b/utils/basic_auth_test.go
index 2ff3050cf..b2caa9c66 100644
--- a/utils/basic_auth_test.go
+++ b/utils/basic_auth_test.go
@@ -145,7 +145,7 @@ func TestVerifyCredential(t *testing.T) {
 		{"foo", "bar", map[string]string{"test": "1234", "foo": hashedPasswords["bar"]}, true},
 		{"foo", "1234", map[string]string{"test": "1234", "foo": hashedPasswords["bar"]}, false},
 		{"none", "1234", map[string]string{"test": "1234", "foo": hashedPasswords["bar"]}, false},
-		{"test", "1234", map[string]string{"test": "1234" + string(0), "foo": hashedPasswords["bar"]}, false},
+		{"test", "1234", map[string]string{"test": "12340", "foo": hashedPasswords["bar"]}, false},
 	}
 
 	for _, tt := range verifyCredentialTests {
diff --git a/utils/dataconverter_test.go b/utils/dataconverter_test.go
index ae9564071..b7dd8a699 100644
--- a/utils/dataconverter_test.go
+++ b/utils/dataconverter_test.go
@@ -170,14 +170,14 @@ func TestNewDurationSecondsConverter(t *testing.T) {
 
 func TestDurationSecondsConverterConvert(t *testing.T) {
 	mS := &DurationSecondsConverter{}
-	if _, err := mS.Convert("string"); err.Error() != "time: invalid duration string" {
+	if _, err := mS.Convert("string"); err.Error() != "time: invalid duration \"string\"" {
 		t.Error(err)
 	}
 }
 
 func TestDurationNanosecondsConverterConvert(t *testing.T) {
 	nS := &DurationNanosecondsConverter{}
-	if _, err := nS.Convert("string"); err.Error() != "time: invalid duration string" {
+	if _, err := nS.Convert("string"); err.Error() != "time: invalid duration \"string\"" {
 		t.Error(err)
 	}
 }