--- a/tools/tryselect/push.py
+++ b/tools/tryselect/push.py
@@ -1,14 +1,15 @@
 # This Source Code Form is subject to the terms of the Mozilla Public
 # License, v. 2.0. If a copy of the MPL was not distributed with this
 # file, You can obtain one at http://mozilla.org/MPL/2.0/.
 
 from __future__ import absolute_import, print_function
 
+import hashlib
 import json
 import os
 import sys
 
 from mozboot.util import get_state_dir
 from mozbuild.base import MozbuildObject
 from mozversioncontrol import get_repository_object, MissingVCSExtension
 
@@ -39,17 +40,19 @@ UNCOMMITTED_CHANGES = """
 ERROR please commit changes before continuing
 """.strip()
 
 MAX_HISTORY = 10
 
 here = os.path.abspath(os.path.dirname(__file__))
 build = MozbuildObject.from_environment(cwd=here)
 vcs = get_repository_object(build.topsrcdir)
-history_path = os.path.join(get_state_dir()[0], 'history', 'try_task_configs.json')
+topsrcdir_hash = hashlib.sha256(os.path.abspath(build.topsrcdir)).hexdigest()
+history_path = os.path.join(get_state_dir()[0], 'history', topsrcdir_hash, 'try_task_configs.json')
+old_history_path = os.path.join(get_state_dir()[0], 'history', 'try_task_configs.json')
 
 
 def write_task_config(try_task_config):
     config_path = os.path.join(vcs.path, 'try_task_config.json')
     with open(config_path, 'w') as fh:
         json.dump(try_task_config, fh, indent=2, separators=(',', ':'))
         fh.write('\n')
     return config_path

--- a/tools/tryselect/selectors/again.py
+++ b/tools/tryselect/selectors/again.py
@@ -1,19 +1,20 @@
 # This Source Code Form is subject to the terms of the Mozilla Public
 # License, v. 2.0. If a copy of the MPL was not distributed with this
 # file, You can obtain one at http://mozilla.org/MPL/2.0/.
 
 from __future__ import absolute_import, print_function, unicode_literals
 
 import json
 import os
+import shutil
 
 from ..cli import BaseTryParser
-from ..push import push_to_try, history_path
+from ..push import push_to_try, history_path, old_history_path
 
 
 class AgainParser(BaseTryParser):
     name = 'again'
     arguments = [
         [['--index'],
          {'default': 0,
           'type': int,
@@ -32,16 +33,22 @@ class AgainParser(BaseTryParser):
           'action': 'store_true',
           'help': "Remove all history and exit",
           }],
     ]
     common_groups = ['push']
 
 
 def run_try_again(index=0, purge=False, list_configs=False, message='{msg}', **pushargs):
+    # Try to move existing history file from the old location to the new one.
+    if os.path.isfile(old_history_path) and not os.path.isfile(history_path):
+        if not os.path.isdir(os.path.dirname(history_path)):
+            os.makedirs(os.path.dirname(history_path))
+        shutil.move(old_history_path, history_path)
+
     if purge:
         os.remove(history_path)
         return
 
     if not os.path.isfile(history_path):
         print("error: history file not found: {}".format(history_path))
         return 1