As you all are aware that Codeunit 1 (Application Management) has been removed and it is replace with new system codeunits. By moving this there is no functionality changes but this process will affect upgrade process for NAV.

All these functions has been changed  to different event including publishers and subscribers that means instead of calling Codeunit 1 functions business central will use system codeunits.

Following tables will illustrate mapping between codeunit 1 triggers and event publishers.

Codeunit 1 trigger	New Codeunit ID	New method
CompanyClose	LogInManagement	CompanyClose
CompanyOpen	LogInManagement	CompanyOpen
GetSystemIndicator	LogInManagement	GetSystemIndicator
OnAfterCompanyClose	LogInManagement	OnAfterCompanyClose
OnAfterCompanyOpen	LogInManagement	OnAfterCompanyOpen
OnBeforeCompanyClose	LogInManagement	OnBeforeCompanyClose
OnBeforeCompanyOpen	LogInManagement	OnBeforeCompanyOpen
FindPrinter	ReportManagement	GetPrinterName
ApplicationVersion	Application System Constants	ApplicationVersion
CustomApplicationVersion	N/A	N/A
ReleaseVersion	Application System Constants	ReleaseVersion
ApplicationBuild	Application System Constants	ApplicationBuild
CustomApplicationBuild	N/A	N/A
ApplicationLanguage	LanguageManagement	ApplicationLanguage
DefaultRoleCenter	Conf./Personalization Mgt.	DefaultRoleCenterID
MakeDateTimeText	TextManagement	MakeDateTimeText
GetSeparateDateTime	TextManagement	GetSeparateDateTime
MakeDateText	TextManagement	MakeDateText
MakeTimeText	TextManagement	MakeTimeText
MakeText	TextManagement	MakeText
MakeDateTimeFilter	TextManagement	MakeDateTimeFilter
MakeDateFilter	TextManagement	MakeDateFilter
MakeTextFilter	TextManagement	MakeTextFilter
MakeCodeFilter	TextManagement	MakeTextFilter
MakeTimeFilter	TextManagement	MakeTimeFilter
AutoFormatTranslate	AutoFormatManagement	AutoFormatTranslate
ReadRounding	AutoFormatManagement	ReadRounding
CaptionClassTranslate	CaptionManagement	CaptionClassTranslate
GetCueStyle	Cue Setup	GetCueStyle
SetGlobalLanguage	LanguageManagement	SetGlobalLanguage
ValidateApplicationlLanguage	LanguageManagement	ValidateApplicationLanguage
LookupApplicationlLanguage	LanguageManagement	LookupApplicationLanguage
GetGlobalTableTriggerMask	GlobalTriggerManagement	GetGlobalTableTriggerMask
OnGlobalInsert	GlobalTriggerManagement	OnGlobalInsert
OnGlobalModify	GlobalTriggerManagement	OnGlobalModify
OnGlobalDelete	GlobalTriggerManagement	OnGlobalDelete
OnGlobalRename	GlobalTriggerManagement	OnGlobalRename
GetDatabaseTableTriggerSetup	GlobalTriggerManagement	GetDatabaseTableTriggerSetup
OnDatabaseInsert	GlobalTriggerManagement	OnDatabaseInsert
OnDatabaseModify	GlobalTriggerManagement	OnDatabaseModify
OnDatabaseDelete	GlobalTriggerManagement	OnDatabaseDelete
OnDatabaseRename	GlobalTriggerManagement	OnDatabaseRename
OnDebuggerBreak	Debugger Management	ProcessOnDebuggerBreak
LaunchDebugger	Debugger Management	OpenDebugger
OpenSettings	Conf./Personalization Mgt.	OpenSettings
OpenContactMSSales	SaaS Log In Management	OpenContactMSSales
InvokeExtensionInstallation	ExtensionMarketplaceMgmt	InvokeExtensionInstallation
CustomizeChart	Generic Chart Mgt	CustomizeChart
HasCustomLayout	ReportManagement	HasCustomLayout
MergeDocument	ReportManagement	MergeDocument
ReportGetCustomRdlc	ReportManagement	ReportGetCustomRdlc
ReportScheduler	ReportManagement	ScheduleReport
OnBeforeOpenSettings	Conf./Personalization Mgt.	OnBeforeOpenSettings
OnAfterGetApplicationVersion	Application System Constants	OnAfterGetApplicationVersion
OnRoleCenterOpen	Conf./Personalization Mgt.	OnRoleCenterOpen
OnAfterGetSystemIndicator	Sales-Post and Send	OnAfterGetSystemIndicator
OnAfterFindPrinter	ReportManagement	OnAfterGetPrinterName
OnAfterGetDefaultRoleCenter	Conf./Personalization Mgt.	OnAfterGetDefaultRoleCenter
OnAfterMakeDateText	N/A	N/A
OnAfterMakeTimeText	N/A	N/A
OnAfterMakeText	N/A	N/A
OnAfterMakeDateTimeFilter	TextManagement	OnAfterMakeDateTimeFilter
OnAfterMakeDateFilter	TextManagement	OnAfterMakeDateFilter
OnAfterMakeTextFilter	TextManagement	OnAfterMakeTextFilter
OnAfterMakeCodeFilter	N/A	N/A
OnAfterMakeTimeFilter	TextManagement	OnAfterMakeTimeFilter
OnAfterAutoFormatTranslate	AutoFormatManagement	OnAfterAutoFormatTranslate
OnAfterCaptionClassTranslate	CaptionManagement	OnAfterCaptionClassTranslate
OnAfterGetGlobalTableTriggerMask	GlobalTriggerManagement	OnAfterGetGlobalTableTriggerMask
OnAfterOnGlobalInsert	GlobalTriggerManagement	OnAfterOnGlobalInsert
OnAfterOnGlobalModify	GlobalTriggerManagement	OnAfterOnGlobalModify
OnAfterOnGlobalDelete	GlobalTriggerManagement	OnAfterOnGlobalDelete
OnAfterOnGlobalRename	GlobalTriggerManagement	OnAfterOnGlobalRename
OnAfterGetDatabaseTableTriggerSetup	GlobalTriggerManagement	OnAfterGetDatabaseTableTriggerSetup
OnAfterOnDatabaseInsert	GlobalTriggerManagement	OnAfterOnDatabaseInsert
OnAfterOnDatabaseModify	GlobalTriggerManagement	OnAfterOnDatabaseModify
OnAfterOnDatabaseDelete	GlobalTriggerManagement	OnAfterOnDatabaseDelete
OnAfterOnDatabaseRename	GlobalTriggerManagement	OnAfterOnDatabaseRename
OnAfterHasCustomLayout	ReportManagement	OnAfterHasCustomLayout
OnAfterReportGetCustomRdlc	Edit MS Word Report Layout	OnAfterReportGetCustomRdlc
OnBeforeOnDatabaseInsert	GlobalTriggerManagement	OnBeforeOnDatabaseInsert
OnBeforeOnDatabaseModify	GlobalTriggerManagement	OnBeforeOnDatabaseModify
OnBeforeOnDatabaseDelete	GlobalTriggerManagement	OnBeforeOnDatabaseDelete
OnBeforeOnDatabaseRename	GlobalTriggerManagement	OnBeforeOnDatabaseRename
OnEditInExcel	ODataUtility	OnEditInExcel
OnInstallAppPerDatabase	N/A	N/A
OnInstallAppPerCompany	N/A	N/A
OnCheckPreconditionsPerDatabase	Data Upgrade Mgt.	OnCheckPreconditionsPerDatabase
OnCheckPreconditionsPerCompany	Data Upgrade Mgt.	RaiseOnCheckPreconditionsPerCompany
OnUpgradePerDatabase	Data Upgrade Mgt.	OnUpgradePerDatabase
OnUpgradePerCompany	Data Upgrade Mgt.	OnUpgradePerCompany
OnValidateUpgradePerDatabase	Data Upgrade Mgt.	OnValidateUpgradePerDatabase
OnValidateUpgradePerCompany	Data Upgrade Mgt.	OnValidateUpgradePerCompany

Hope this helps you