getting error after updating angular core & angular cli from v5.1 to v7.2

ive updated the angular core form 5.1 to 7.2 also angular-cli

after when i try to serve my application it gives me error The serve command requires to be run in an Angular project, but a project definition could not be found.

thanks

Angular Cli Error: The serve command requires to be run in an Angular project, but a project definition could not be found

already tried this solution but it didn't work

here is my version description

Angular CLI: 7.2.2
Node: 8.11.1
OS: win32 x64
Angular: 5.2.11
... animations, common, compiler, compiler-cli, core, forms
... http, language-service, platform-browser
... platform-browser-dynamic, router

Package                      Version
------------------------------------------------------
@angular-devkit/architect    0.12.2
@angular-devkit/core         7.2.2
@angular-devkit/schematics   7.2.2
@angular/cli                 7.2.2
@schematics/angular          7.2.2
@schematics/update           0.12.2
rxjs                         5.5.12
typescript                   2.5.3

Solution

Have you tried killing your serve command first and then starting it? basically, you need to restart it. Also, make sure you are running it in the right place.