Angular 6: ERROR TypeError: Cannot read property 'toLowerCase' of undefined

change the

baseUrl: 'http://locahost:4200/users';

to

baseUrl= 'http://locahost:4200/users';

since the type of baseUrl is string

Error Solved !!! The Error is due to the colon:

baseUrl: 'http://locahost:4200/users';

Use '=' in place of ':' because baseUrl is string.

baseUrl='http://locahost:4200/users';