Hello all.
I am trying to assign a user some role in my Dynamics 365 for Sales (CRM) and I get the error:

Error log:
Unhandled exception:
Exception type: System.ServiceModel.FaultException`1[Microsoft.Xrm.Sdk.OrganizationServiceFault]
Message: System.Web.HttpUnhandledException (0x80004005): Exception of type 'System.Web.HttpUnhandledException' was thrown. ---> Microsoft.Crm.CrmException: OrganizationServiceFault System.NullReferenceException: Object reference not set to an instance of an object.
at Microsoft.Dynamics.FOCommon.Plugins.Services.DualWriteSecurityRoleAssociateService.PreAssociate(LocalPluginContext localcontext)
at Microsoft.Dynamics.FOCommon.Plugins.PluginBase.Execute(IServiceProvider serviceProvider)
at Microsoft.Crm.Dialogs.RoleDialogPage.ConfigureForm()
at Microsoft.Crm.Application.Controls.AppUIPage.OnPreRender(EventArgs e)
at Microsoft.Crm.Application.Controls.AppPage.OnPreRender(EventArgs e)
at System.Web.UI.Control.PreRenderRecursiveInternal()
at System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint)
at System.Web.UI.Page.HandleError(Exception e)
at System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint)
at System.Web.UI.Page.ProcessRequest(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint)
at System.Web.UI.Page.ProcessRequest()
at System.Web.UI.Page.ProcessRequest(HttpContext context)
at System.Web.HttpApplication.CallHandlerExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute()
at System.Web.HttpApplication.ExecuteStepImpl(IExecutionStep step)
at System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously): Microsoft Dynamics CRM has experienced an error. Reference number for administrators or support: #0E9723BBDetail:
<OrganizationServiceFault xmlns:i="">www.w3.org/.../XMLSchema-instance" xmlns="">schemas.microsoft.com/.../Contracts">
<ActivityId>a541dbbb-2aaf-4f56-89cf-bf54bdf51ea4</ActivityId>
<ErrorCode>-2147220970</ErrorCode>
<ErrorDetails xmlns:d2p1="">schemas.datacontract.org/.../System.Collections.Generic" />
<HelpLink i:nil="true" />
<Message>System.Web.HttpUnhandledException (0x80004005): Exception of type 'System.Web.HttpUnhandledException' was thrown. ---> Microsoft.Crm.CrmException: OrganizationServiceFault System.NullReferenceException: Object reference not set to an instance of an object.
at Microsoft.Dynamics.FOCommon.Plugins.Services.DualWriteSecurityRoleAssociateService.PreAssociate(LocalPluginContext localcontext)
at Microsoft.Dynamics.FOCommon.Plugins.PluginBase.Execute(IServiceProvider serviceProvider)
at Microsoft.Crm.Dialogs.RoleDialogPage.ConfigureForm()
at Microsoft.Crm.Application.Controls.AppUIPage.OnPreRender(EventArgs e)
at Microsoft.Crm.Application.Controls.AppPage.OnPreRender(EventArgs e)
at System.Web.UI.Control.PreRenderRecursiveInternal()
at System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint)
at System.Web.UI.Page.HandleError(Exception e)
at System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint)
at System.Web.UI.Page.ProcessRequest(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint)
at System.Web.UI.Page.ProcessRequest()
at System.Web.UI.Page.ProcessRequest(HttpContext context)
at System.Web.HttpApplication.CallHandlerExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute()
at System.Web.HttpApplication.ExecuteStepImpl(IExecutionStep step)
at System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously): Microsoft Dynamics CRM has experienced an error. Reference number for administrators or support: #0E9723BB</Message>
<Timestamp>2020-09-22T11:26:27.3634109Z</Timestamp>
<ExceptionRetriable>false</ExceptionRetriable>
<ExceptionSource i:nil="true" />
<InnerFault>
<ActivityId>a541dbbb-2aaf-4f56-89cf-bf54bdf51ea4</ActivityId>
<ErrorCode>-2147220891</ErrorCode>
<ErrorDetails xmlns:d3p1="">schemas.datacontract.org/.../System.Collections.Generic" />
<HelpLink i:nil="true" />
<Message>OrganizationServiceFault System.NullReferenceException: Object reference not set to an instance of an object.
at Microsoft.Dynamics.FOCommon.Plugins.Services.DualWriteSecurityRoleAssociateService.PreAssociate(LocalPluginContext localcontext)
at Microsoft.Dynamics.FOCommon.Plugins.PluginBase.Execute(IServiceProvider serviceProvider)</Message>
<Timestamp>2020-09-22T11:26:27.3634109Z</Timestamp>
<ExceptionRetriable>false</ExceptionRetriable>
<ExceptionSource i:nil="true" />
<InnerFault i:nil="true" />
<OriginalException i:nil="true" />
<TraceText>
[Microsoft.Dynamics.FOCommon.Plugins: Microsoft.Dynamics.FOCommon.Plugins.DualWriteSecurityRoleAssociate]
[cd9cdb58-9c5b-e911-a955-000d3a1d5d5a: Microsoft.Dynamics.FOCommon.Plugins.DualWriteSecurityRoleAssociate: Associate of any Entity]
</TraceText>
</InnerFault>
<OriginalException i:nil="true" />
<TraceText i:nil="true" />
</OrganizationServiceFault>
Please, tell me how to fix this error