--- a/taskcluster/ci/source-test/python.yml
+++ b/taskcluster/ci/source-test/python.yml
@@ -86,17 +86,17 @@ mochitest-harness:
             - 'testing/mozbase/moztest/moztest/selftest/**'
             - 'testing/mozharness/mozharness/base/log.py'
             - 'testing/mozharness/mozharness/mozilla/structuredlog.py'
             - 'testing/mozharness/mozharness/mozilla/testing/errors.py'
             - 'testing/profiles/**'
 
 mozbase:
     description: testing/mozbase unit tests
-    python-version: [2]
+    python-version: [2, 3]
     treeherder:
         symbol: mb
     run:
         using: python-test
         subsuite: mozbase
     when:
         files-changed:
             - 'testing/mozbase/**'

--- a/testing/mozbase/manifestparser/tests/manifest.ini
+++ b/testing/mozbase/manifestparser/tests/manifest.ini
@@ -1,10 +1,11 @@
 [DEFAULT]
 subsuite = mozbase, os == "linux"
+skip-if = python == 3
 [test_expressionparser.py]
 [test_manifestparser.py]
 [test_testmanifest.py]
 [test_read_ini.py]
 [test_convert_directory.py]
 [test_filters.py]
 [test_chunking.py]
 

--- a/testing/mozbase/mozcrash/tests/manifest.ini
+++ b/testing/mozbase/mozcrash/tests/manifest.ini
@@ -1,8 +1,8 @@
 [DEFAULT]
 subsuite = mozbase, os == "linux"
-
+skip-if = python == 3
 [test_basic.py]
 [test_java_exception.py]
 [test_save_path.py]
 [test_stackwalk.py]
 [test_symbols_path.py]

--- a/testing/mozbase/mozdebug/tests/manifest.ini
+++ b/testing/mozbase/mozdebug/tests/manifest.ini
@@ -1,4 +1,4 @@
 [DEFAULT]
 subsuite = mozbase, os == "linux"
-
+skip-if = python == 3
 [test.py]

--- a/testing/mozbase/mozfile/tests/manifest.ini
+++ b/testing/mozbase/mozfile/tests/manifest.ini
@@ -1,9 +1,13 @@
 [DEFAULT]
 subsuite = mozbase, os == "linux"
 [test_extract.py]
+skip-if = python == 3
 [test_load.py]
+skip-if = python == 3
 [test_move_remove.py]
+skip-if = python == 3
 [test_tempdir.py]
 [test_tempfile.py]
+skip-if = python == 3
 [test_tree.py]
 [test_url.py]

--- a/testing/mozbase/mozhttpd/tests/manifest.ini
+++ b/testing/mozbase/mozhttpd/tests/manifest.ini
@@ -1,8 +1,9 @@
 [DEFAULT]
 subsuite = mozbase, os == "linux"
+skip-if = python == 3
 [api.py]
 [baseurl.py]
 [basic.py]
 [filelisting.py]
 [paths.py]
 [requestlog.py]

--- a/testing/mozbase/mozinfo/tests/manifest.ini
+++ b/testing/mozbase/mozinfo/tests/manifest.ini
@@ -1,3 +1,4 @@
 [DEFAULT]
 subsuite = mozbase, os == "linux"
+skip-if = python == 3
 [test.py]

--- a/testing/mozbase/mozinstall/tests/manifest.ini
+++ b/testing/mozbase/mozinstall/tests/manifest.ini
@@ -1,7 +1,7 @@
 [DEFAULT]
 subsuite = mozbase, os == "linux"
-
+skip-if = python == 3
 [test_binary.py]
 [test_install.py]
 [test_is_installer.py]
 [test_uninstall.py]

--- a/testing/mozbase/mozlog/tests/manifest.ini
+++ b/testing/mozbase/mozlog/tests/manifest.ini
@@ -1,6 +1,9 @@
 [DEFAULT]
 subsuite = mozbase, os == "linux"
 [test_logger.py]
+skip-if = python == 3
 [test_logtypes.py]
 [test_formatters.py]
+skip-if = python == 3
 [test_structured.py]
+skip-if = python == 3

--- a/testing/mozbase/moznetwork/tests/manifest.ini
+++ b/testing/mozbase/moznetwork/tests/manifest.ini
@@ -1,3 +1,4 @@
 [DEFAULT]
 subsuite = mozbase, os == "linux"
+skip-if = python == 3
 [test.py]

--- a/testing/mozbase/mozprocess/tests/manifest.ini
+++ b/testing/mozbase/mozprocess/tests/manifest.ini
@@ -1,10 +1,10 @@
 [DEFAULT]
 subsuite = mozbase, os == "linux"
-
+skip-if = python == 3
 [test_kill.py]
 [test_misc.py]
 [test_poll.py]
 [test_wait.py]
 [test_output.py]
 [test_params.py]
 [test_process_reader.py]

--- a/testing/mozbase/mozprofile/tests/manifest.ini
+++ b/testing/mozbase/mozprofile/tests/manifest.ini
@@ -1,10 +1,11 @@
 [DEFAULT]
 subsuite = mozbase, os == "linux"
+skip-if = python == 3
 [test_addonid.py]
 [test_server_locations.py]
 [test_preferences.py]
 [test_permissions.py]
 [test_bug758250.py]
 [test_nonce.py]
 [test_clone_cleanup.py]
 [test_profile.py]

--- a/testing/mozbase/mozrunner/tests/manifest.ini
+++ b/testing/mozbase/mozrunner/tests/manifest.ini
@@ -1,9 +1,10 @@
 [DEFAULT]
 subsuite = mozbase, os == "linux"
+skip-if = python == 3
 [test_crash.py]
 [test_interactive.py]
 [test_start.py]
 [test_states.py]
 [test_stop.py]
 [test_threads.py]
 [test_wait.py]

--- a/testing/mozbase/moztest/tests/manifest.ini
+++ b/testing/mozbase/moztest/tests/manifest.ini
@@ -1,4 +1,5 @@
 [DEFAULT]
 subsuite = mozbase, os == "linux"
+skip-if = python == 3
 [test.py]
 [test_resolve.py]

--- a/testing/mozbase/mozversion/tests/manifest.ini
+++ b/testing/mozbase/mozversion/tests/manifest.ini
@@ -1,4 +1,5 @@
 [DEFAULT]
 subsuite = mozbase, os == "linux"
+skip-if = python == 3
 [test_binary.py]
 [test_apk.py]