Application Management Codeunit Replacement

What does it mean: Application Management Codeunit Replacement

Yes, it's true. Application Management Coueunit 1 is no more exists in Dynamics 365 Business Central.

What's about the function? 

Are they exists? 

Where these are placed now? 

.

.

To many questions????

Don't worry, see this link - Codeunit 1 Replacement

Does this transition impact upgrade. Yes, see the solution as well in that link. 

How does these transition made? Where are those functions?

All available triggers / functions / events are now placed in System Codeunit and Management Codeunits.

See this link to get the details - Transitioning from Codeunit 1 to System Codeunits

Below are list of management codeunits where triggers / functions / events are moved now (except System Codeunits):

Type	ID	Name
Codeunit	40	LogInManagement
Codeunit	41	TextManagement
Codeunit	42	CaptionManagement
Codeunit	43	LanguageManagement
Codeunit	44	ReportManagement
Codeunit	45	AutoFormatManagement
Codeunit	49	GlobalTriggerManagement
Codeunit	50	SaaS Log In Management
Codeunit	79	Sales-Post and Send
Codeunit	2501	ExtensionMarketplaceMgmt
Codeunit	6710	ODataUtility
Codeunit	9015	Application System Constants
Codeunit	9170	Conf./Personalization Mgt.
Codeunit	9180	Generic Chart Mgt
Codeunit	9500	Debugger Management
Codeunit	9650	Edit MS Word Report Layout
Codeunit	9701	Cue Setup
Codeunit	9900	Data Upgrade Mgt.