diff --git a/doc/source/dev/dev-quickstart.rst b/doc/source/dev/dev-quickstart.rst
index d2b6206fbf..d8287c691c 100644
--- a/doc/source/dev/dev-quickstart.rst
+++ b/doc/source/dev/dev-quickstart.rst
@@ -144,6 +144,15 @@ To run the unit tests under py34 and also run the pep8 tests::
     # run all tests (unit under py34 and pep8)
     tox -epy34 -epep8
 
+.. note::
+    If tests are run under py27 and then run under py34 or py35 the following error may occur::
+
+      db type could not be determined
+      ERROR: InvocationError: '/home/ubuntu/ironic/.tox/py35/bin/ostestr'
+
+    To overcome this error remove the file `.testrepository/times.dbm`
+    and then run the py34 or py35 test.
+
 You may pass options to the test programs using positional arguments.
 To run a specific unit test, this passes the -r option and desired test
 (regex string) to `os-testr <https://pypi.python.org/pypi/os-testr>`_::