Invalid_Grant whlie generating Access Token using saved Refresh token in Dropbox Sign .NET SDK

[gagsbh]

Hello @Greg-DB ,

I am using the following Dropbox Sign .NET SDK code in my project to generate Dropbox Sign Access token using previously saved Refresh token.

 public async Task<TokenResponse> GetRefreshToken(TokenResponse tokenResponse)

        {

            TokenResponse tokenResponse2 = new TokenResponse();

            string errorlog = ConfigurationManager2.AppSettings("ErrorLog");

            var config = new Configuration();

            var oAuthApi = new OAuthApi(config);

            try

            {

                var data = new OAuthTokenRefreshRequest(refreshToken: tokenResponse.RefreshToken);

                var result = await oAuthApi.OauthTokenRefreshAsync(data);

                if (result != null)

                {

                    tokenResponse2.Expires = result.ExpiresIn;

                    tokenResponse2.AcquireTime = DateTime.Now;

                    tokenResponse2.AccessToken = result.AccessToken;

                    tokenResponse2.RefreshToken = result.RefreshToken; 

                    tokenResponse2.AcquireTime = DateTime.UtcNow;                  

                }               

                return tokenResponse2;

            }            

            catch (ApiException ex)

            {                

                    File.AppendAllText(errorlog, "\r\n\r\n" + "nGetRefreshToken: - Error");

                    File.AppendAllText(errorlog, "\r\nException when calling Dropbox Sign API: " + ex.Message);

                    File.AppendAllText(errorlog, "\r\nStatus Code: " + ex.ErrorCode);

                    File.AppendAllText(errorlog, "\r\nStack Trace: " +  ex.StackTrace);

    throw ex;

            }

            catch (Exception ex)

            {

                File.AppendAllText(errorlog, "\r\nGetRefreshToken - Error");

                File.AppendAllText(errorlog, "\r\n" + ex.Message + "\r\n" + ex.StackTrace);

            }

            return tokenResponse;

        }

I am getting the following Error Message and Stack Trace.

Error converting value "invalid_grant" to type 'Dropbox.Sign.Model.ErrorResponseError'. Path 'error', line 1, position 24.
at Newtonsoft.Json.Serialization.JsonSerializerInternalReader.EnsureType(JsonReader reader, Object value, CultureInfo culture, JsonContract contract, Type targetType)
at Newtonsoft.Json.Serialization.JsonSerializerInternalReader.CreateValueInternal(JsonReader reader, Type objectType, JsonContract contract, JsonProperty member, JsonContainerContract containerContract, JsonProperty containerMember, Object existingValue)
at Newtonsoft.Json.Serialization.JsonSerializerInternalReader.SetPropertyValue(JsonProperty property, JsonConverter propertyConverter, JsonContainerContract containerContract, JsonProperty containerProperty, JsonReader reader, Object target)
at Newtonsoft.Json.Serialization.JsonSerializerInternalReader.PopulateObject(Object newObject, JsonReader reader, JsonObjectContract contract, JsonProperty member, String id)
at Newtonsoft.Json.Serialization.JsonSerializerInternalReader.CreateObject(JsonReader reader, Type objectType, JsonContract contract, JsonProperty member, JsonContainerContract containerContract, JsonProperty containerMember, Object existingValue)
at Newtonsoft.Json.Serialization.JsonSerializerInternalReader.CreateValueInternal(JsonReader reader, Type objectType, JsonContract contract, JsonProperty member, JsonContainerContract containerContract, JsonProperty containerMember, Object existingValue)
at Newtonsoft.Json.Serialization.JsonSerializerInternalReader.Deserialize(JsonReader reader, Type objectType, Boolean checkAdditionalContent)
at Newtonsoft.Json.JsonSerializer.DeserializeInternal(JsonReader reader, Type objectType)
at Newtonsoft.Json.JsonConvert.DeserializeObject(String value, Type type, JsonSerializerSettings settings)
at Newtonsoft.Json.JsonConvert.DeserializeObject[T](String value, JsonSerializerSettings settings)
at Dropbox.Sign.Client.Configuration.<>c.<.cctor>b__78_0(String methodName, IApiResponse response)
at Dropbox.Sign.Api.OAuthApi.OauthTokenRefreshWithHttpInfoAsync(OAuthTokenRefreshRequest oAuthTokenRefreshRequest, Int32 operationIndex, CancellationToken cancellationToken)
at Dropbox.Sign.Api.OAuthApi.OauthTokenRefreshAsync(OAuthTokenRefreshRequest oAuthTokenRefreshRequest, Int32 operationIndex, CancellationToken cancellationToken)
at SGCloudMigration.Business.DropboxSignUtility.GetRefreshToken(TokenResponse tokenResponse, String relationshipname) in D:\SG Cloud Migration\SGCloudMigration.Business.Core\DropboxSignUtility.cs:line 364

Please  help.

Thanks,

Gagan

[Spencer H · Accepted solution]

[Cross-linking for reference: https://stackoverflow.com/questions/78296262/why-am-i-getting-invalid-grant-error-while-using-refres... ]

Hi Gagan,

Thank you for reaching out, it looks like you are receiving an invalid_grant error. This error typically occurs when using a stored refresh token and one of the following is true: 

 - Scopes for the OAuth API app have changed
 - The user revoked authorization to the OAuth API app
 - The OAuth API app is approved multiple times by the same user—this will cause the previous authorization to reset and a new refresh token to be generated.

If any of these actions have occurred, please try completing the authorization process again for the user to generate a new access_token and refresh_token. Try using the new refresh_token to generate any new access_token after the initial access_token expires. Please see our OAuth Walkthrough documentation for more details.

If the issue persists, please submit a support request, along with the code snippet you just provided, so we can further assist you in determining why that error is being thrown. Thanks!

[gagsbh]

Thank you for the reply.

For me, the issue was due to:

- The OAuth API app is approved multiple times by the same user—this will cause the previous authorization to reset and a new refresh token to be generated.