Brief summary

After cancelling an add-on download by closing the Add-on Store dialog and choosing "Yes" to cancel the download, reopening the Add-on Store and starting another download raises an exception:

AttributeError: 'NoneType' object has no attribute 'submit'

If the Add-on Store is then closed again, NVDA may raise a second exception:

AttributeError: 'NoneType' object has no attribute 'shutdown'

Steps to reproduce

1. Open Add-on Store.
2. Start downloading any add-on from the Available add-ons tab.
3. Close the Add-on Store dialog.
4. When NVDA asks whether to cancel the in-progress download, choose "Yes".
5. Reopen Add-on Store.
6. Start downloading another add-on.

Optional extra confirmation:

7. Close the Add-on Store again and choose "Yes" to cancel.

Actual behavior

The second download does not start. NVDA logs an unhandled exception:

Traceback (most recent call last):
  File "gui\addonStoreGui\controls\actions.pyc", line 154, in _menuItemClicked
  File "gui\addonStoreGui\viewModels\action.pyc", line 99, in _actionHandler
  File "gui\addonStoreGui\viewModels\store.pyc", line 372, in installOverrideIncompatibilityForAddon
  File "gui\addonStoreGui\viewModels\store.pyc", line 526, in getAddon
  File "addonStore\network.pyc", line 137, in download
AttributeError: 'NoneType' object has no attribute 'submit'

If the user closes the Add-on Store again after this failed second attempt, NVDA may log:

Traceback (most recent call last):
  File "gui\addonStoreGui\controls\storeDialog.pyc", line 255, in onClose
  File "gui\addonStoreGui\viewModels\store.pyc", line 732, in cancelDownloads
  File "addonStore\network.pyc", line 202, in cancelAll
AttributeError: 'NoneType' object has no attribute 'shutdown'

Because the failed item still appears to be downloading, a later close attempt with "No" also keeps the Add-on Store dialog open.

Expected behavior

After cancelling a download, the Add-on Store should remain usable.

• Reopening the Add-on Store and downloading another add-on should work normally.
• Closing the Add-on Store again should not raise any exception.

NVDA logs, crash dumps and other attachments

Relevant log excerpt included above

System Configuration

NVDA type

• portable copy / source copy

NVDA version

• Runing from source

Have you tried any other versions of NVDA? If so, please report their behaviors.

In version 2025.3, the add-on store cannot be opened after canceling the download, making testing impossible.

Windows version

Windows 10 22H2

Name and version of other software in use when reproducing the issue

• None required beyond NVDA Add-on Store

Other information about your system

None

Troubleshooting steps

Does the issue still occur after restarting your computer?

Yes

If NVDA add-ons are disabled, is your problem still occurring?

Yes

Does the issue still occur after you run the System Accessibility Repair Tool?

Yes