Getting Access token is empty error while running msgraph-sdk-go training example code

While trying to run the msgraph-sdk-go training code from here: https://github.com/microsoftgraph/msgraph-training-go, I'm getting InvalidAuthenticationTokenmsg: Access token is empty while executing the Graph API calls.
I configured a Microsoft developer account with instant sandbox for trial purpose.
I created an app registration as mentioned in the tutorial here and granted required permissions for the app.
The code is able to get the AppToken, but for calls to get Users, it fails with the above error. Am I missing something here?

I tried below code from the example for msgraph-training

func (g *GraphHelper) InitializeGraphForAppAuth() error {
clientId := os.Getenv("CLIENT_ID")
tenantId := os.Getenv("TENANT_ID")
clientSecret := os.Getenv("CLIENT_SECRET")
credential, err := azidentity.NewClientSecretCredential(tenantId, clientId, clientSecret, nil)
if err != nil {
return err
}
g.clientSecretCredential = credential
// Create an auth provider using the credential
authProvider, err := auth.NewAzureIdentityAuthenticationProviderWithScopes(g.clientSecretCredential, []string{
"https://graph.microsoft.com/.default",
})
if err != nil {
return err
}
// Create a request adapter using the auth provider
adapter, err := msgraphsdk.NewGraphRequestAdapter(authProvider)
if err != nil {
return err
}
// Create a Graph client using request adapter
client := msgraphsdk.NewGraphServiceClient(adapter)
g.appClient = client
return nil
}
// This part works, and I get the AppToken with required scope, once decoded.
func (g *GraphHelper) GetAppToken() (*string, error) {
token, err := g.clientSecretCredential.GetToken(context.Background(), policy.TokenRequestOptions{
Scopes: []string{
"https://graph.microsoft.com/.default",
},
})
if err != nil {
return nil, err
}
fmt.Println("expires on : ", token.ExpiresOn)
return &token.Token, nil
}
// The GetUsers function errors out
func (g *GraphHelper) GetUsers() (models.UserCollectionResponseable, error) {
var topValue int32 = 25
query := users.UsersRequestBuilderGetQueryParameters{
// Only request specific properties
Select: []string{"displayName", "id", "mail"},
// Get at most 25 results
Top: &topValue,
// Sort by display name
Orderby: []string{"displayName"},
}
resp, err := g.appClient.Users().
Get(context.Background(),
&users.UsersRequestBuilderGetRequestConfiguration{
QueryParameters: &query,
})
if err != nil {
fmt.Println("Users.Get got Error", err.Error(), resp)
printOdataError(err)
}
resp, err = g.appClient.Users().
Get(context.Background(),
nil)
if err != nil {
fmt.Println("Users.Get got Error with nil", err.Error(), resp)
}
return resp, err
}

I have added the User.Read.All permission in the app as mentioned in the tutorial.
Instead of getting the list of users, I'm getting below error:

Users.Get got Error error status code received from the API <nil>
error: error status code received from the API
code: InvalidAuthenticationTokenmsg: Access token is empty.Users.Get got Error with nil error status code received from the API <nil>

As you are using client Credential Flow ,you can verify your permission in azure portal , if you have User.Read.All delegated permission , Removes the delegated ones and add the corresponding application ones and don't forget to click on grant administrator consent after that. It should then work.

Hope this helps

Thanks.

Okay, so the fix that did work for me after trial and error was a version mismatch in the example and the actual application I was trying out.
The version of the beta msgraph application I was using was v0.49, whereas the msgraphsdk tutorial was using v0.48. The go mod command picked up the latest v0.49 initially I guess, I updated the go.mod file to use v0.48 after looking at the go.mod file from msgraph-training repository and things started working.<br/>
Hope this helps someone else later on.