I kept getting this error in Report Configuration Manager/Change Database to a remote Report Server database. I'm using a SQL Server Credential instead of Service Credentials.
System.Data.SqlClient.SqlException (0x80131904): Cannot alter the role 'RSExecRole', because it does not exist or you do not have permission.
at System.Data.SqlClient.SqlConnection.OnError(SqlException exception, Boolean breakConnection, Action`1 wrapCloseInAction)
at System.Data.SqlClient.TdsParser.ThrowExceptionAndWarning(TdsParserStateObject stateObj, Boolean callerHasConnectionLock, Boolean asyncClose)
at System.Data.SqlClient.TdsParser.TryRun(RunBehavior runBehavior, SqlCommand cmdHandler, SqlDataReader dataStream, BulkCopySimpleResultSet bulkCopyHandler, TdsParserStateObject stateObj, Boolean& dataReady)
at System.Data.SqlClient.SqlCommand.RunExecuteNonQueryTds(String methodName, Boolean async, Int32 timeout, Boolean asyncWrite)
at System.Data.SqlClient.SqlCommand.InternalExecuteNonQuery(TaskCompletionSource`1 completion, String methodName, Boolean sendToPipe, Int32 timeout, Boolean& usedCache, Boolean asyncWrite, Boolean inRetry)
at System.Data.SqlClient.SqlCommand.ExecuteNonQuery()
at Microsoft.ReportingServices.Common.DBUtils.ApplyScript(SqlConnection conn, String script, ICommandWrapperFactory commandWrapper)
at Microsoft.ReportingServices.Common.DBUtils.ApplyScript(String connectionString, String script)
at ReportServicesConfigUI.SqlClientTools.SqlTools.ApplyScript(String connectionString, String script)
ClientConnectionId:3b2a05b4-4463-4170-8285-89e2b88f198c
Error Number:15151,State:1,Class:16
The RSExecRole are both the master, msdb, and ReportServer database. The SQL Server account I'm using also have DB owner on ReportServer DB and member of RSExecRole on both master and msdb.