My SharePoint 2016 development environment was throwing an exception after saving sites as template.
I discovered that the issue occurred during the solution activation, it was a validation error:

“The ‘ListInternal’ attribute is not allowed”

I’ve found xsd schema in the Hive folder at this path:

“C:\Program Files\Common Files\microsoft shared\Web Server Extensions\16\TEMPLATE\XML\wss.xsd”

Comparing this file with another one took from a working enviroment, I’ve found that “ListInternal” attribute was missing.

Adding this string to wss.xsd solved the issue:

 <xs:attribute name="ListInternal" type="xs:string" /> 

 

Hope this helps 🙂

 

EXCEPTION:

Microsoft.SharePoint.SPException: Feature definition with Id 0644a50d-3451-4534-916a-40b6316ef791 failed validation, file ‘aaaaaaListInstances\ElementsFields.xml’, line 533, character 265: The ‘ListInternal’ attribute is not allowed.
at Microsoft.SharePoint.Administration.SPSolutionPackage.FeatureXmlValidationCallback.XmlValidationCallBack(Object sender, ValidationEventArgs evtargs)
at System.Xml.Schema.XmlSchemaValidator.SendValidationEvent(String code, String arg)
at System.Xml.Schema.XmlSchemaValidator.ValidateAttribute(String lName, String ns, XmlValueGetter attributeValueGetter, String attributeStringValue, XmlSchemaInfo schemaInfo)
at System.Xml.Schema.XmlSchemaValidator.ValidateAttribute(String localName, String namespaceUri, XmlValueGetter attributeValue, XmlSchemaInfo schemaInfo)
at System.Xml.XsdValidatingReader.ValidateAttributes()
at System.Xml.XsdValidatingReader.ProcessElementEvent()
at System.Xml.XsdValidatingReader.Read()
at System.Xml.XmlReader.MoveToContent()
at System.Xml.XmlReader.IsStartElement()
at Microsoft.SharePoint.Utilities.SPUtility.XsdValidateXml(XmlTextReader xmlStreamReader, String friendlyName, String pathXsdFile, String tagExpectedRootNode, Int32 desiredPathVersion, ValidationEventHandler xsdValEventHandler)
at Microsoft.SharePoint.Administration.SPSolutionPackage.SolutionFile.ValidateFeatureXmlFile(String rootTagElement)
at Microsoft.SharePoint.Administration.SPSolutionPackage.AddFeatureElementsCore(XmlNodeList nodeList, String strFeatureDirRelativeToCabFile, Guid featureId, Dictionary`2 filesAdded)
at Microsoft.SharePoint.Administration.SPSolutionPackage.AddFeatureElements(XmlNode root, String strFeatureDirRelativeToCabFile, String strFeatureXmlFilename, Guid featureId)
at Microsoft.SharePoint.Administration.SPSolutionPackage.WspSolutionFeature.ProcessFeatureXml()
at Microsoft.SharePoint.Administration.SPSolutionPackage.InitSolutionFeatures(XmlNode root)
at Microsoft.SharePoint.Administration.SPSolutionPackage.ProcessSolutionManifest()
at Microsoft.SharePoint.Administration.SPSolutionPackage.Load()
at Microsoft.SharePoint.Administration.SPSolutionLanguagePack.CreateSolutionPackage(SPRequest request, String name, String signature, Byte[] fileBytes)
at Microsoft.SharePoint.SPUserSolutionCollection.c__DisplayClass4.b__0()
at Microsoft.SharePoint.Utilities.SecurityContext.RunAsProcess(CodeToRunElevated secureCode)
at Microsoft.SharePoint.SPUserSolutionCollection.AddOrUpgrade(SPListItem item, SPUserSolution existingSolution)
at Microsoft.SharePoint.SPUserSolutionCollection.Add(Int32 solutionGalleryItemId)
at Microsoft.SharePoint.SPSolutionExporter.ExportWebToGallery(SPWeb web, String solutionFileName, String title, String description, ExportMode exportMode, Boolean includeContent, String workflowTemplateName, String destinationListUrl, Action`1 solutionPostProcessor, Boolean activateSolution)