This blog explains how to customize the base app of business central (old fashion) .
Please Don’t customize the base app, Use extension wherever possible
Step 1 :- Copy Base Application from installer

Step 2 :- Unzip in designated folder .This contains app.json file where in target set to onprem

app.json will look like this

Step 3 :- Download the symbols
Step 4:- Add the following in either user settings/workspace settings . This is required for .NET DLL used in application

Step 5 :- Unpublish the base application and dependencies or else you will get an error stating that extension already deployed on tenant
Use following PowerShell command
Unpublish-NavApp -Name “Base Application” -ServerInstance BC150
Step 6:- Import license file and publish the modified app.
Hope this will help you.
Hi amol, I need training for web service and API is it possible for u
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Hi
Web service creation or consuming web services in BC?
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