1С:Enterprise mode
Designer mode
1. 1С:Enterprise mode:
Select Advanced tools / Functions for Technician...:
Click on + sign besides Standard > Manage configuration extensions:
Uncheck the option Check applicability when adding and loading extensions.
Click on Add and the browse option will open and path at which extension file is saved should be selected.
Once the file is selected, the following message will be received.
Press Yes and repeat the action.
If the extension does not appear in the table, repeat, starting with Add.
Uncheck the safe mode, profile name and unsafe operation protection. 
System will give a Security Warning message > select Yes.
Then restart the application.
2. Designer mode:
Open the database by clicking on the Designer button:
Go to Administration > Active Users and check that nobody is using 1C right now.
All users should log out.
Go to Administration > Dump Infobase and create backup.
The name of backup file should include the current date and words 'before the update'.
Go to Configuration > Open configuration:
Configuration is open:
Go to Configuration > Configuration extensions:
The following page is open - create a new configuration extension
Extension appears in the list:
As extension is created, go to Configuration > Load configuration from the file:
As configuration is not empty, be notified by the system:
As full configuration loaded, go to update:
Extension is installed:
Now uncheck the safe mode, profile name and unsafe operation protection.
Then restart the application.
Thank you for being a FirstBIT customer!