Hi,
I'm trying to upgrade from 4.3.4 to current 5.0-latest (5.0.6, I think) - but I have some errors, maybe anyone can assist/help me a little bit 
But two things won't work:
- plone.app.relationfield Update 1.2.1 > 1.2.3
breaks all my Relations - pa.multilingual 2.0.1 -> 3.0.17 lost every connections between languages (de|en), either in portal_catalog are only "de" Objects
- after enter manual en-URL -> edit and save, it seems to work (Items is visible again, but not linked with de-Translation)
Maybe an interessting connection: https://github.com/plone/Products.CMFPlone/issues/1671
Traceback
<z3c.relationfield.relation.RelationValue object at 0x1109ad6e0>
>>> for r in obj.relation:
... print r.to_object
Traceback (most recent call last):
File "<console>", line 3, in <module>
File "/Users/user/Projects/.buildout/eggs/z3c.relationfield-0.7-py2.7.egg/z3c/relationfield/relation.py", line 43, in to_object
return _object(self.to_id)
File "/Users/user/Projects/.buildout/eggs/z3c.relationfield-0.7-py2.7.egg/z3c/relationfield/relation.py", line 110, in _object
intids = component.getUtility(IIntIds)
File "/Users/user/Projects/.buildout/eggs/zope.component-3.9.5-py2.7.egg/zope/component/_api.py", line 169, in getUtility
raise ComponentLookupError(interface, name)
ComponentLookupError: (<InterfaceClass zope.intid.interfaces.IIntIds>, '')
```
----------
What I've done:
**on current DB (4.3.4)**
* remove wildcard-foldercontents (and dependencies: jarn.jsi18n)
* collective.js.jqueryui
* Plone jQuery Integration
* LDAP Support (which breaks on p5 buildout?!)
* update portal_title umlaut ( https://github.com/plone/Products.CMFPlone/issues/1633)
* pack db
* clear & rebuild catalog
**on 4-latest**
* uninstall "Plone jQuery Integration"
* reinstall all products where reinstall, if one breaks it is ok ( https://community.plone.org/t/plone-migration-4-3-4-to-5-0-errors/1507) Plone Upgrade should solve it
* @@plone-upgrade
* clear & rebuild catalog
**on 5-latest**
* reinstall all products where reinstall, if one breaks it is ok (p5 Upgrade should solve it :-) )
Everything works after a few manual Steps ( https://github.com/plone/plone.app.upgrade/issues/84; https://gist.github.com/2silver/e3ef53ac37b296b87b2091ca07e94a6b)
(edit restructure)