Unable to evaluate template language function 'resourceId': the type 'Microsoft.Compute/virtualMachines/extensions' requires '2' resource name argument

My ARM template code fails with the following validation error.

New-azResourceGroupDeployment : 10:41:07 - Error: Code=InvalidTemplate; Message=Deployment template validation failed: 'The template resource 'DI-XXX-UKW-DB1/joindomain' at line '439' and column '9' is
not valid: Unable to evaluate template language function 'resourceId': the type 'Microsoft.Compute/virtualMachines/extensions' requires '2' resource name argument(s). Please see
https://aka.ms/arm-template-expressions/#resourceid for usage details.. Please see https://aka.ms/arm-template-expressions for usage details.
```

{
"type": "Microsoft.Compute/virtualMachines/extensions",
"name": "[concat(variables('varnodeNamePrefix'),copyindex(1),'/extensions')]",
"apiVersion": "2017-03-30",
"location": "[variables('varlocation')]",
"dependsOn": [
"[concat(variables('varnodeNamePrefix'),copyindex(1))]"
],
"properties": {
"publisher": "Microsoft.Compute",
"type": "CustomScriptExtension",
"typeHandlerVersion": "1.8",
"autoUpgradeMinorVersion": true,
"settings": {
"fileUris": [
"/sqlcluster/InstallAdditionalModules.ps1"
]
},
"protectedSettings": {
"commandToExecute": "powershell.exe -ExecutionPolicy Unrestricted ./sqlcluster/InstallAdditionalModules.ps1",
"storageAccountName": "fsdfsdfsdf",
"storageAccountKey": "sdfsdfsdfsdfsdfsdfsdf/BH9C+sdfsdfsdfsdfsdfsdfsdf+4K2dEbAnWZ5DZTzPQ=="
}
},
"copy": {
"name": "WinFeatures",
"count":"[variables('varvmCount')]"
}
},

{
"apiVersion": "2015-06-15",
"type": "Microsoft.Compute/virtualMachines/extensions",
"name": "[concat(variables('varnodeNamePrefix'),copyindex(1),'/joindomain')]",
"location": "[resourceGroup().location]",
"dependsOn": [
"[resourceId(resourceGroup().location,'Microsoft.Compute/virtualMachines/extensions', concat( variables('varnodeNamePrefix'),copyindex(1),'/extensions') ) ]"
],
"properties": {
"publisher": "Microsoft.Compute",
"type": "JsonADDomainExtension",
"typeHandlerVersion": "1.3",
"autoUpgradeMinorVersion": true,
"settings": {
"Name": "[variables('vardomainToJoin')]",
"User": "[concat(variables('vardomainToJoin'), '\\', variables('vardomainUsername'))]",
"Restart": "true",
"Options": "[variables('vardomainJoinOptions')]"
},
"protectedSettings": {
"Password": "[variables('vardomainPassword')]"
}
},
"copy": {
"name": "joindomain",
"count":"[variables('varvmCount')]"
}
```

Start with the two Microsoft.Compute/virtualMachines/extensions resource definitions shown in the issue and review the resourceId function usage in the linked ARM template documentation. Compare the dependency expression with the extension resource's nested name structure, then validate the template and confirm deployment validation succeeds without the resourceId argument error.

Written by the indexing model from the issue text.