I'm getting the following error in Sitecore 10.1 when Installing Unicorn

    Unknown connection string. Name: '$(1)'
    
    Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code.
    
    Exception Details: System.InvalidOperationException: Unknown connection string. Name: '$(1)'
    
    Source Error:
    
    An unhandled exception was generated during the execution of the current web request. Information regarding the origin and location of the exception can be identified using the exception stack trace below.
    
Stack trace


    [InvalidOperationException: Unknown connection string. Name: '$(1)']
       Sitecore.Configuration.DefaultSettings.GetConnectionString(String connectionStringName) +384
       Sitecore.Configuration.DefaultFactory.CreateFromConnectionStringName(XmlNode configNode, String[] parameters, Boolean assert) +182
       Sitecore.Configuration.DefaultFactory.CreateObject(XmlNode configNode, String[] parameters, Boolean assert, IFactoryHelper helper) +188
       Sitecore.Configuration.DefaultFactory.CreateObject(XmlNode configNode, String[] parameters, Boolean assert) +72
       Sitecore.Configuration.DefaultFactory.GetConstructorParameters(XmlNode configNode, String[] parameters, Boolean assert) +161
       Sitecore.Configuration.DefaultFactory.CreateFromTypeName(XmlNode configNode, String[] parameters, Boolean assert) +114
       Sitecore.Configuration.DefaultFactory.CreateObject(XmlNode configNode, String[] parameters, Boolean assert, IFactoryHelper helper) +163
       Sitecore.Configuration.DefaultFactory.CreateObject(XmlNode configNode, String[] parameters, Boolean assert) +72
       Sitecore.Configuration.DefaultFactory.CreateObject(String configPath, String[] parameters, Boolean assert) +703
       Sitecore.Configuration.DefaultFactory.CreateFromReference(XmlNode configNode, String[] parameters, Boolean assert) +170
       Sitecore.Configuration.DefaultFactory.CreateObject(XmlNode configNode, String[] parameters, Boolean assert, IFactoryHelper helper) +116
       Sitecore.Configuration.DefaultFactory.CreateObject(XmlNode configNode, String[] parameters, Boolean assert) +72
       Sitecore.Configuration.DefaultFactory.GetInnerObject(XmlNode paramNode, String[] parameters, Boolean assert) +842
       Sitecore.Configuration.DefaultFactory.AssignProperties(XmlNode configNode, String[] parameters, Object obj, Boolean assert, Boolean deferred, IFactoryHelper helper) +545
       Sitecore.Configuration.DefaultFactory.CreateObject(XmlNode configNode, String[] parameters, Boolean assert, IFactoryHelper helper) +326
       Sitecore.Configuration.DefaultFactory.CreateObject(XmlNode configNode, String[] parameters, Boolean assert) +72
       Sitecore.Configuration.DefaultFactory.CreateObject(String configPath, String[] parameters, Boolean assert) +703
       Sitecore.Configuration.DefaultFactory.GetDatabase(String name, Boolean assert) +157
       Sitecore.Configuration.DefaultFactory.GetDatabase(String name) +55
       Sitecore.Configuration.DefaultFactory.GetDatabases() +121
       Sitecore.Data.SqlServer.SqlServerLinkDataProviderFactory.CreateProvidersForAllDatabases() +161
    
    [TargetInvocationException: Exception has been thrown by the target of an invocation.]
       System.RuntimeMethodHandle.InvokeMethod(Object target, Object[] arguments, Signature sig, Boolean constructor) +0
       System.Reflection.RuntimeMethodInfo.UnsafeInvokeInternal(Object obj, Object[] parameters, Object[] arguments) +269
       System.Reflection.RuntimeMethodInfo.Invoke(Object obj, BindingFlags invokeAttr, Binder binder, Object[] parameters, CultureInfo culture) +146
       Sitecore.Reflection.ReflectionUtil.CallStaticMethod(String typeName, String methodName, Object[] parameters) +165
       Sitecore.Configuration.DefaultFactory.CreateFromFactoryMethod(XmlNode configNode, String[] parameters, Boolean assert) +534
       Sitecore.Configuration.DefaultFactory.CreateObject(XmlNode configNode, String[] parameters, Boolean assert, IFactoryHelper helper) +91
       Sitecore.Configuration.DefaultFactory.CreateObject(XmlNode configNode, String[] parameters, Boolean assert) +72
       Sitecore.Configuration.DefaultFactory.GetConstructorParameters(XmlNode configNode, String[] parameters, Boolean assert) +161
       Sitecore.Configuration.DefaultFactory.CreateFromTypeName(XmlNode configNode, String[] parameters, Boolean assert) +114
       Sitecore.Configuration.DefaultFactory.CreateObject(XmlNode configNode, String[] parameters, Boolean assert, IFactoryHelper helper) +163
       Sitecore.Configuration.DefaultFactory.CreateObject(XmlNode configNode, String[] parameters, Boolean assert) +72
       Sitecore.Configuration.DefaultFactory.CreateObject(String configPath, String[] parameters, Boolean assert) +703
       Sitecore.Configuration.DefaultFactory.GetLinkDatabase() +36
       Sitecore.DefaultGlobals.Load() +294
       (Object , Object ) +55
       Sitecore.Pipelines.CorePipeline.Run(PipelineArgs args) +490
       Sitecore.Pipelines.DefaultCorePipelineManager.Run(String pipelineName, PipelineArgs args, String pipelineDomain, Boolean failIfNotExists) +236
       Sitecore.Pipelines.DefaultCorePipelineManager.Run(String pipelineName, PipelineArgs args, String pipelineDomain) +22
       Sitecore.Nexus.Web.HttpModule.Application_Start() +146
       Sitecore.Nexus.Web.HttpModule.Init(HttpApplication app) +898
       System.Web.HttpApplication.RegisterEventSubscriptionsWithIIS(IntPtr appContext, HttpContext context, MethodInfo[] handlers) +584
       System.Web.HttpApplication.InitSpecial(HttpApplicationState state, MethodInfo[] handlers, IntPtr appContext, HttpContext context) +168
       System.Web.HttpApplicationFactory.GetSpecialApplicationInstance(IntPtr appContext, HttpContext context) +277
       System.Web.Hosting.PipelineRuntime.InitializeApplication(IntPtr appContext) +369
    
    [HttpException (0x80004005): Exception has been thrown by the target of an invocation.]
       System.Web.HttpRuntime.FirstRequestInit(HttpContext context) +532
       System.Web.HttpRuntime.EnsureFirstRequestInit(HttpContext context) +111
       System.Web.HttpRuntime.ProcessRequestNotificationPrivate(IIS7WorkerRequest wr, HttpContext context) +724