--- a/testing/mozbase/mozlog/mozlog/pytest_mozlog/plugin.py
+++ b/testing/mozbase/mozlog/mozlog/pytest_mozlog/plugin.py
@@ -79,19 +79,23 @@ class MozLog(object):
             # If an xfail unexpectedly passes, the 'call' report has .failed (Pytest 2)
             # or .passed (Pytest 3), so we leave status as PASS (!= expected)
             # to log an unexpected result.
             expected = 'FAIL'
             if report.skipped:  # indicates expected failure (passing test)
                 status = 'FAIL'
         elif report.failed:
             status = 'FAIL' if report.when == 'call' else 'ERROR'
-            crash = report.longrepr.reprcrash  # here longrepr is a ReprExceptionInfo
-            message = "{0} (line {1})".format(crash.message, crash.lineno)
-            stack = report.longrepr.reprtraceback
+            try:
+                crash = report.longrepr.reprcrash  # here longrepr is a ReprExceptionInfo
+                message = "{0} (line {1})".format(crash.message, crash.lineno)
+                stack = report.longrepr.reprtraceback
+            except AttributeError:
+                # When using pytest-xdist, longrepr is serialised as a str
+                message = stack = report.longrepr
         elif report.skipped:  # indicates true skip
             status = expected = 'SKIP'
             message = report.longrepr[-1]  # here longrepr is a tuple (file, lineno, reason)
         if status != expected or expected != 'PASS':
             self.results[test] = (status, expected, message, stack)
         if report.when == 'teardown':
             defaults = ('PASS', 'PASS', None, None)
             status, expected, message, stack = self.results.get(test, defaults)