Fix TypeError

changelog/5782.bugfix.rst

@@ -0,0 +1 @@
+Fix decoding error when printing an error response from ``--pastebin``.

src/_pytest/pastebin.py

@@ -72,7 +72,7 @@ def create_new_paste(contents):
     if m:
         return "{}/show/{}".format(url, m.group(1))
     else:
-        return "bad response: " + response
+        return "bad response: " + response.decode("utf-8")
 
 
 def pytest_terminal_summary(terminalreporter):

testing/test_pastebin.py

@@ -116,3 +116,15 @@ def test_create_new_paste(self, pastebin, mocked_urlopen):
         assert "lexer=%s" % lexer in data.decode()
         assert "code=full-paste-contents" in data.decode()
         assert "expiry=1week" in data.decode()
+
+    def test_create_new_paste_failure(self, pastebin, monkeypatch):
+        import io
+        import urllib.request
+
+        def response(url, data):
+            stream = io.BytesIO(b"something bad occurred")
+            return stream
+
+        monkeypatch.setattr(urllib.request, "urlopen", response)
+        result = pastebin.create_new_paste(b"full-paste-contents")
+        assert result == "bad response: something bad occurred"