Error when saving configuration

[CyrilleB79]

Steps to reproduce:

• Create a profile for Notepad and use default profile for Windows Explorer
• Focus the Notepad
• Modify a configuration parameter, e.g. press NVDA+P to modify symbol level.
• Press NVDA+control+R to restore to saved configuration
• Alt+Tab to Windows Explorer
• Modify a configuration parameter, e.g. press NVDA+P to modify symbol level.
• Press NVDA+control+C to save the current configuration.

Actual behavior:

A dialog appears with the following message:
"Cannot save configuration - file system is probably write protected"

Expected behavior:

No error message and configuration saved correctly.

System configuration

NVDA installed/portable/running from source:

Installed

NVDA version:

2021.3.1

Windows version:

Windows 10 2004 (x64) build 19041.388

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

N/A

Other information about your system:

N/A

Other questions

Does the issue still occur after restarting your computer?

Yes

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

No

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

Yes

Does the issue still occur after you run the COM Registration Fixing Tool in NVDA's tools menu?

Not tested

Here is the log:
log.txt

[feerrenrut]

I don't think this is a regression, certainly something to fix though.
Looks like something is holding onto the notepad profile key, from the log:

INFO - config.ConfigManager.save (22:19:34.803) - MainThread (7008):
Base configuration saved
WARNING - config.ConfigManager.save (22:19:34.803) - MainThread (7008):
Error saving configuration; probably read only file system
DEBUGWARNING - config.ConfigManager.save (22:19:34.803) - MainThread (7008):
Traceback (most recent call last):
  File "config\__init__.pyc", line 538, in save
KeyError: 'notepad'