Backport PR pandas-dev#29294 for 0.25.3 whatsnew

Author: jbrockmendel

pandas/io/parsers.py

@@ -2935,7 +2935,7 @@ def _next_iter_line(self, row_num):
             if self.warn_bad_lines or self.error_bad_lines:
                 msg = str(e)
 
-                if "NULL byte" in msg:
+                if "NULL byte" in msg or "line contains NUL" in msg:
                     msg = (
                         "NULL byte detected. This byte "
                         "cannot be processed in Python's "

pandas/tests/io/parser/test_common.py

@@ -1898,10 +1898,7 @@ def test_null_byte_char(all_parsers):
         out = parser.read_csv(StringIO(data), names=names)
         tm.assert_frame_equal(out, expected)
     else:
-        if compat.PY38:
-            msg = "line contains NUL"
-        else:
-            msg = "NULL byte detected"
+        msg = "NULL byte detected"
         with pytest.raises(ParserError, match=msg):
             parser.read_csv(StringIO(data), names=names)