C program linking SQLSERVER database: instance failed

C# Program links SqlServer database ： Instance failed

We write a linked database in a common class, as shown in the following figure ：

If you find this is OK, you will not report an error

But write the above connection string in config Words in the configuration file , The above error will be reported , The reason is because of config The escape character is not required for the connection string in , So remove a backslash \ That's all right. ！