Issues while downgrading from 2211 to 2205

[nasesantosh]

I've initially upgraded my Platform version from 2205 to 2211 and later on when I'm trying to downgrade from 2211 to 2205, I'm getting below Error

java.lang.IllegalArgumentException: extension 'alluicommons' not found within de.hybris.bootstrap.typesystem.YTypeSystem@1ff81fcb at de.hybris.bootstrap.xml.XMLContentHandler.endElement(XMLContentHandler.java:203) at java.xml/com.sun.org.apache.xerces.internal.parsers.AbstractSAXParser.endElement(AbstractSAXParser.java:618) at java.xml/com.sun.org.apache.xerces.internal.impl.XMLDocumentFragmentScannerImpl.scanEndElement(XMLDocumentFragmentScannerImpl.java:1728) at java.xml/com.sun.org.apache.xerces.internal.impl.XMLDocumentFragmentScannerImpl$FragmentContentDriver.next(XMLDocumentFragmentScannerImpl.java:2899) at java.xml/com.sun.org.apache.xerces.internal.impl.XMLDocumentScannerImpl.next(XMLDocumentScannerImpl.java:605) at java.xml/com.sun.org.apache.xerces.internal.impl.XMLNSDocumentScannerImpl.next(XMLNSDocumentScannerImpl.java:112) at java.xml/com.sun.org.apache.xerces.internal.impl.XMLDocumentFragmentScannerImpl.scanDocument(XMLDocumentFragmentScannerImpl.java:542) at java.xml/com.sun.org.apache.xerces.internal.parsers.XML11Configuration.parse(XML11Configuration.java:889) at java.xml/com.sun.org.apache.xerces.internal.parsers.XML11Configuration.parse(XML11Configuration.java:825) at java.xml/com.sun.org.apache.xerces.internal.parsers.XMLParser.parse(XMLParser.java:141) at java.xml/com.sun.org.apache.xerces.internal.parsers.AbstractSAXParser.parse(AbstractSAXParser.java:1224) at java.xml/com.sun.org.apache.xerces.internal.jaxp.SAXParserImpl$JAXPSAXParser.parse(SAXParserImpl.java:637) at java.xml/com.sun.org.apache.xerces.internal.jaxp.SAXParserImpl.parse(SAXParserImpl.java:326) at de.hybris.bootstrap.xml.Parser.parse(Parser.java:291) at de.hybris.bootstrap.xml.Parser.parse(Parser.java:275) at de.hybris.bootstrap.typesystem.xml.HybrisTypeSystemParser.parseExtensionSystem(HybrisTypeSystemParser.java:115) at de.hybris.bootstrap.typesystem.YTypeSystemSource.readTypeSystem(YTypeSystemSource.java:102) ... 40 more Caused by: de.hybris.bootstrap.xml.UnknownParseError: error parsing system backoffice at lines [151-182] : extension 'alluicommons' not found within de.hybris.bootstrap.typesystem.YTypeSystem@1ff81fcb

[alemasetto]

You still have references of newer item types in your database.
Try to clean the "Orphaned Types" in HAC > Maintenance or with ant https://me.sap.com/notes/0002149792

ant clearOrphanedTypes