Server error is displayed on Add Company form when try to add new company.

Server error is displayed on Add Company form when try to add new company.
Replication Steps:
1. Login as Partner
2. Click on Employer Administration -> Add Company
3. Provide valid data in All the fields
4. Click on Save & Continue button.

Expected Result:
Server error should not bedisplayed on Add Company form when try to add new company.

Actual Result:
Server error is displayed on Add Company form when try to add new company.

CC: Saurabh SablakaRakesh RoySachin HingoleHrishikesh DeshpandeSamir

Exception : String reference not set to an instance of a String.Parameter name: s
App Error Log : -
Employee ID : 0
Action Name : SaveComapyInformation
Model : System.Web.Mvc.HandleErrorInfo
Controller : Configuration
Web Error Log : at System.Text.Encoding.GetBytes(String s)
at WORKTERRA.SharedFunction.CreateJWTTokenForClientCredentialFlow(String clientSecret, String clientId, String audience)
at WORKTERRA.SharedFunction.GetOneIAMAccessTokenForClientCredentialFlow()
at WORKTERRA.SharedFunction.CheckSanctionedCompanies(SanctionAPICompanyDTO objSanctionAPIUserDetails, String accessPath, Hashtable& objsaveToDB)
at WORKTERRA.Shared.Areas.Configuration.Controllers.ConfigurationController.SaveComapyInformation(CompanyInformationModel objCompanyInformationModel)
at lambda_method(Closure , ControllerBase , Object[] )
at System.Web.Mvc.ReflectedActionDescriptor.Execute(ControllerContext controllerContext, IDictionary`2 parameters)
at System.Web.Mvc.ControllerActionInvoker.InvokeActionMethod(ControllerContext controllerContext, ActionDescriptor actionDescriptor, IDictionary`2 parameters)
at System.Web.Mvc.ControllerActionInvoker.<>c_DisplayClass15.<InvokeActionMethodWithFilters>b_12()
at System.Web.Mvc.ControllerActionInvoker.InvokeActionMethodFilter(IActionFilter filter, ActionExecutingContext preContext, Func`1 continuation)
at System.Web.Mvc.ControllerActionInvoker.InvokeActionMethodFilter(IActionFilter filter, ActionExecutingContext preContext, Func`1 continuation)
at System.Web.Mvc.ControllerActionInvoker.InvokeActionMethodWithFilters(ControllerContext controllerContext, IList`1 filters, ActionDescriptor actionDescriptor, IDictionary`2 parameters)
at System.Web.Mvc.ControllerActionInvoker.InvokeAction(ControllerContext controllerContext, String actionName)

Error LOG
Exception : Object reference not set to an instance of an object.
App Error Log : -
Employee ID : 0
Action Name : AddUpdateCompany
Model : System.Web.Mvc.HandleErrorInfo
Controller : Configuration
Web Error Log : at WORKTERRA.SharedFunction.APICall(String url, String method, String contentType)
at WORKTERRA.SharedFunction.GetOneIAMAccessTokenForClientCredentialFlow()
at WORKTERRA.SharedFunction.CheckSanctionedCompanies(SanctionAPICompanyDTO objSanctionAPIUserDetails, String accessPath, Hashtable& objsaveToDB)
at WORKTERRA.Shared.Areas.Configuration.Controllers.ConfigurationController.AddUpdateCompany(AddNewCompanyModel objAddNewCompanyModel)
at lambda_method(Closure , ControllerBase , Object[] )
at System.Web.Mvc.ReflectedActionDescriptor.Execute(ControllerContext controllerContext, IDictionary`2 parameters)
at System.Web.Mvc.ControllerActionInvoker.InvokeActionMethod(ControllerContext controllerContext, ActionDescriptor actionDescriptor, IDictionary`2 parameters)
at System.Web.Mvc.ControllerActionInvoker.<>c_DisplayClass15.<InvokeActionMethodWithFilters>b_12()
at System.Web.Mvc.ControllerActionInvoker.InvokeActionMethodFilter(IActionFilter filter, ActionExecutingContext preContext, Func`1 continuation)
at System.Web.Mvc.ControllerActionInvoker.InvokeActionMethodFilter(IActionFilter filter, ActionExecutingContext preContext, Func`1 continuation)
at System.Web.Mvc.ControllerActionInvoker.InvokeActionMethodWithFilters(ControllerContext controllerContext, IList`1 filters, ActionDescriptor actionDescriptor, IDictionary`2 parameters)
at System.Web.Mvc.ControllerActionInvoker.InvokeAction(ControllerContext controllerContext, String actionName)