diff --git a/pymisp/api.py b/pymisp/api.py
index 33f2793..c41edd5 100644
--- a/pymisp/api.py
+++ b/pymisp/api.py
@@ -3027,9 +3027,6 @@ class PyMISP:
         else:
             raise MISPServerError("please fill path or data parameter")
 
-        if isinstance(to_post, bytes):
-            to_post = to_post.decode()
-
         if str(version) == '1':
             url = urljoin(self.root_url, 'events/upload_stix')
             response = self._prepare_request('POST', url, data=to_post, output_type='xml', content_type='xml')  # type: ignore
@@ -3505,21 +3502,20 @@ class PyMISP:
     def __repr__(self):
         return f'<{self.__class__.__name__}(url={self.root_url})'
 
-    def _prepare_request(self, request_type: str, url: str, data: Union[str, Iterable, Mapping, AbstractMISP] = {}, params: Mapping = {},
+    def _prepare_request(self, request_type: str, url: str, data: Union[Iterable, Mapping, AbstractMISP, bytes] = {}, params: Mapping = {},
                          kw_params: Mapping = {}, output_type: str = 'json', content_type: str = 'json') -> requests.Response:
         '''Prepare a request for python-requests'''
         if url[0] == '/':
             # strip it: it will fail if MISP is in a sub directory
             url = url[1:]
         url = urljoin(self.root_url, url)
-        if data == {} or isinstance(data, str):
+        if data == {} or isinstance(data, bytes):
             d = data
         elif data:
-            if not isinstance(data, str):  # Else, we already have a text blob to send
-                if isinstance(data, dict):  # Else, we can directly json encode.
-                    # Remove None values.
-                    data = {k: v for k, v in data.items() if v is not None}
-                d = json.dumps(data, default=pymisp_json_default)
+            if isinstance(data, dict):  # Else, we can directly json encode.
+                # Remove None values.
+                data = {k: v for k, v in data.items() if v is not None}
+            d = json.dumps(data, default=pymisp_json_default)
 
         logger.debug(f'{request_type} - {url}')
         if d is not None:
diff --git a/tests/stix1.xml-utf8 b/tests/stix1.xml-utf8
new file mode 100644
index 0000000..4c4e149
--- /dev/null
+++ b/tests/stix1.xml-utf8
@@ -0,0 +1,110 @@
+<stix:STIX_Package
+	xmlns:cyboxCommon="http://cybox.mitre.org/common-2"
+	xmlns:cybox="http://cybox.mitre.org/cybox-2"
+	xmlns:cyboxVocabs="http://cybox.mitre.org/default_vocabularies-2"
+	xmlns:AccountObj="http://cybox.mitre.org/objects#AccountObject-2"
+	xmlns:ArtifactObj="http://cybox.mitre.org/objects#ArtifactObject-2"
+	xmlns:ASObj="http://cybox.mitre.org/objects#ASObject-1"
+	xmlns:AddressObj="http://cybox.mitre.org/objects#AddressObject-2"
+	xmlns:PortObj="http://cybox.mitre.org/objects#PortObject-2"
+	xmlns:DomainNameObj="http://cybox.mitre.org/objects#DomainNameObject-1"
+	xmlns:EmailMessageObj="http://cybox.mitre.org/objects#EmailMessageObject-2"
+	xmlns:FileObj="http://cybox.mitre.org/objects#FileObject-2"
+	xmlns:HTTPSessionObj="http://cybox.mitre.org/objects#HTTPSessionObject-2"
+	xmlns:HostnameObj="http://cybox.mitre.org/objects#HostnameObject-1"
+	xmlns:MutexObj="http://cybox.mitre.org/objects#MutexObject-2"
+	xmlns:PipeObj="http://cybox.mitre.org/objects#PipeObject-2"
+	xmlns:URIObj="http://cybox.mitre.org/objects#URIObject-2"
+	xmlns:WinRegistryKeyObj="http://cybox.mitre.org/objects#WinRegistryKeyObject-2"
+	xmlns:WinServiceObj="http://cybox.mitre.org/objects#WinServiceObject-2"
+	xmlns:NetworkConnectionObj="http://cybox.mitre.org/objects#NetworkConnectionObject-2"
+	xmlns:NetworkSocketObj="http://cybox.mitre.org/objects#NetworkSocketObject-2"
+	xmlns:SocketAddressObj="http://cybox.mitre.org/objects#SocketAddressObject-1"
+	xmlns:SystemObj="http://cybox.mitre.org/objects#SystemObject-2"
+	xmlns:ProcessObj="http://cybox.mitre.org/objects#ProcessObject-2"
+	xmlns:X509CertificateObj="http://cybox.mitre.org/objects#X509CertificateObject-2"
+	xmlns:WhoisObj="http://cybox.mitre.org/objects#WhoisObject-2"
+	xmlns:WinExecutableFileObj="http://cybox.mitre.org/objects#WinExecutableFileObject-2"
+	xmlns:UnixUserAccountObj="http://cybox.mitre.org/objects#UnixUserAccountObject-2"
+	xmlns:UserAccountObj="http://cybox.mitre.org/objects#UserAccountObject-2"
+	xmlns:WinUserAccountObj="http://cybox.mitre.org/objects#WinUserAccountObject-2"
+	xmlns:CustomObj="http://cybox.mitre.org/objects#CustomObject-1"
+	xmlns:marking="http://data-marking.mitre.org/Marking-1"
+	xmlns:simpleMarking="http://data-marking.mitre.org/extensions/MarkingStructure#Simple-1"
+	xmlns:tlpMarking="http://data-marking.mitre.org/extensions/MarkingStructure#TLP-1"
+	xmlns:et="http://stix.mitre.org/ExploitTarget-1"
+	xmlns:incident="http://stix.mitre.org/Incident-1"
+	xmlns:indicator="http://stix.mitre.org/Indicator-2"
+	xmlns:coa="http://stix.mitre.org/CourseOfAction-1"
+	xmlns:ttp="http://stix.mitre.org/TTP-1"
+	xmlns:ta="http://stix.mitre.org/ThreatActor-1"
+	xmlns:stixCommon="http://stix.mitre.org/common-1"
+	xmlns:stixVocabs="http://stix.mitre.org/default_vocabularies-1"
+	xmlns:stix-ciqidentity="http://stix.mitre.org/extensions/Identity#CIQIdentity3.0-1"
+	xmlns:snortTM="http://stix.mitre.org/extensions/TestMechanism#Snort-1"
+	xmlns:stix="http://stix.mitre.org/stix-1"
+	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+	xmlns:xal="urn:oasis:names:tc:ciq:xal:3"
+	xmlns:xnl="urn:oasis:names:tc:ciq:xnl:3"
+	xmlns:xpil="urn:oasis:names:tc:ciq:xpil:3"
+	xmlns:ORGNAME="https://localhost:8443"
+	xmlns:xlink="http://www.w3.org/1999/xlink"
+	xmlns:ds="http://www.w3.org/2000/09/xmldsig#"
+	xmlns:xs="http://www.w3.org/2001/XMLSchema"
+	 id="ORGNAME:Package-fbe98511-c726-4550-bb2f-46752f4e47c7" version="1.1.1" timestamp="2021-08-24T12:53:38.320654">
+    <stix:STIX_Header>
+        <stix:Title>Export from ORGNAME MISP</stix:Title>
+        <stix:Package_Intent xsi:type="stixVocabs:PackageIntentVocab-1.0">Threat Report</stix:Package_Intent>
+    </stix:STIX_Header>
+    <stix:Related_Packages>
+        <stix:Related_Package>
+            <stix:Package id="ORGNAME:STIXPackage-f90bb8c1-8505-4d74-af34-3dcffec6b6d4" version="1.1.1" timestamp="2021-08-24T10:53:13">
+                <stix:STIX_Header>
+                    <stix:Title>Export from ORGNAME MISP © YADA YADA</stix:Title>
+                    <stix:Package_Intent xsi:type="stixVocabs:PackageIntentVocab-1.0">Threat Report</stix:Package_Intent>
+                </stix:STIX_Header>
+                <stix:Incidents>
+                    <stix:Incident id="ORGNAME:Incident-f90bb8c1-8505-4d74-af34-3dcffec6b6d4" timestamp="2021-08-24T10:53:28" xsi:type='incident:IncidentType'>
+                        <incident:Title>Test Stix</incident:Title>
+                        <incident:External_ID source="MISP Event">612</incident:External_ID>
+                        <incident:Time>
+                            <incident:Incident_Discovery precision="second">2021-08-24T00:00:00</incident:Incident_Discovery>
+                            <incident:Incident_Reported precision="second">2021-08-24T10:53:28</incident:Incident_Reported>
+                        </incident:Time>
+                        <incident:Reporter>
+                            <stixCommon:Identity>
+                                <stixCommon:Name>ORGNAME</stixCommon:Name>
+                            </stixCommon:Identity>
+                        </incident:Reporter>
+                        <incident:Status xsi:type="stixVocabs:IncidentStatusVocab-1.0">New</incident:Status>
+                        <incident:Related_Observables>
+                            <incident:Related_Observable>
+                                <stixCommon:Relationship>Network activity</stixCommon:Relationship>
+                                <stixCommon:Observable id="ORGNAME:Address-0853d51f-0fe7-4d35-b3cb-b96bdbc1f0ee">
+                                    <cybox:Object id="ORGNAME:AddressObject-0853d51f-0fe7-4d35-b3cb-b96bdbc1f0ee">
+                                        <cybox:Properties xsi:type="AddressObj:AddressObjectType" category="ipv4-addr" is_source="true" is_destination="false">
+                                            <AddressObj:Address_Value condition="Equals">8.8.8.8</AddressObj:Address_Value>
+                                        </cybox:Properties>
+                                    </cybox:Object>
+                                </stixCommon:Observable>
+                            </incident:Related_Observable>
+                        </incident:Related_Observables>
+                        <incident:History>
+                            <incident:History_Item>
+                                <incident:Journal_Entry time_precision="second">Event Threat Level: High</incident:Journal_Entry>
+                            </incident:History_Item>
+                            <incident:History_Item>
+                                <incident:Journal_Entry time_precision="second">MISP Tag: misp:tool="misp2stix"</incident:Journal_Entry>
+                            </incident:History_Item>
+                        </incident:History>
+                        <incident:Information_Source>
+                            <stixCommon:Identity>
+                                <stixCommon:Name>ORGNAME</stixCommon:Name>
+                            </stixCommon:Identity>
+                        </incident:Information_Source>
+                    </stix:Incident>
+                </stix:Incidents>
+            </stix:Package>
+        </stix:Related_Package>
+    </stix:Related_Packages>
+</stix:STIX_Package>
diff --git a/tests/testlive_comprehensive.py b/tests/testlive_comprehensive.py
index 6949dfd..f372ec7 100644
--- a/tests/testlive_comprehensive.py
+++ b/tests/testlive_comprehensive.py
@@ -955,8 +955,9 @@ class TestComprehensive(unittest.TestCase):
             response = self.user_misp_connector.add_event(event, metadata=True)
             self.assertEqual(len(response.attributes), 0)  # response should contains zero attributes
 
-            event.info = "New name"
+            event.info = "New name ©"
             response = self.user_misp_connector.update_event(event, metadata=True)
+            self.assertEqual(response.info, event.info)
             self.assertEqual(len(response.attributes), 0)  # response should contains zero attributes
         finally:  # cleanup
             self.admin_misp_connector.delete_event(event)
@@ -2512,11 +2513,15 @@ class TestComprehensive(unittest.TestCase):
     def test_upload_stix(self):
         # FIXME https://github.com/MISP/MISP/issues/4892
         try:
-            # r1 = self.user_misp_connector.upload_stix('tests/stix1.xml', version='1')
-            # print('stix 1', r1.json())
-            # event_stix_one = MISPEvent()
-            # event_stix_one.load(r.)
+            r1 = self.user_misp_connector.upload_stix('tests/stix1.xml-utf8', version='1')
+            print(r1.text)
+            event_stix_one = MISPEvent()
+            event_stix_one.load(r1.json())
             # self.assertEqual(event_stix_one.attributes[0], '8.8.8.8')
+            self.admin_misp_connector.delete_event(event_stix_one)
+            bl = self.admin_misp_connector.delete_event_blocklist(event_stix_one.uuid)
+            self.assertTrue(bl['success'])
+
             r2 = self.user_misp_connector.upload_stix('tests/stix2.json', version='2')
             print(json.dumps(r2.json(), indent=2))
             event_stix_two = MISPEvent()
@@ -2528,10 +2533,11 @@ class TestComprehensive(unittest.TestCase):
             bl = self.admin_misp_connector.delete_event_blocklist(event_stix_two.uuid)
             self.assertTrue(bl['success'])
         finally:
-            # try:
-            #    self.admin_misp_connector.delete_event(event_stix_one)
-            # except Exception:
-            #    pass
+            try:
+                self.admin_misp_connector.delete_event(event_stix_one)
+                self.admin_misp_connector.delete_event_blocklist(event_stix_one.uuid)
+            except Exception:
+                pass
             try:
                 self.admin_misp_connector.delete_event(event_stix_two)
                 self.admin_misp_connector.delete_event_blocklist(event_stix_two.uuid)