Hi Devs, Passing CLIRR is far from sufficient to stay backward compatible or document incompatible changes ! I know that you know that already, but I want you to remind it once more because while I was on the road showcasing a site, I had to discover that a major feature of the site got broken, and it was silently true for a while apparently. I missed some potential leads, which get me really upset, so I waited a while before writing. The cause was a very simple incompatible change introduced in 4.3M2 ! But tracking it down was not easy since this API breakage was not reported in the RN. Here it is: com.xpn.xwiki.objects.classes.PropertyClass#getClassType is no more reporting the full classname of the type, but now drop the "Class" suffix. So, "com.xpn.xwiki.objects.classes.StringClass" become "String", "com.xpn.xwiki.objects.classes.NumberClass" become "Number"... and so on. The unprivileged API com.xpn.xwiki.api.PropertyClass#getClassType() was also impacted since "StringClass" become "String", "NumberClass" become "Number" and so on. The javadoc of the latter function get updated, meaning that we were really conscious a breakage was done here. Even more conscious, the following was applied in the toXML() method: String classType = getClassType(); if (this.getClass().getSimpleName().equals(classType + "Class")) { // Keep exporting the full Java class name for old/default property types to avoid breaking the XAR format // (to allow XClasses created with the current version of XWiki to be imported in an older version). classType = this.getClass().getName(); } The com.xpn.xwiki.objects.meta.MetaClass was also, since it was using those name as property names. Some compatibility change was applied as well, with explicit comments. But apparently, no one notice (including myself !), and this incompatible change goes through without even a mention in the RN, nor in the the jira issue (XWIKI-8355). So guys, I have no intend to blame anyone here, but I couldn't warn you more about potential consequence of incompatible changes. These need to be discuss, or at least clearly mentioned in the RN. Do not rely on CLIRR for doing the job, it don't. Probably adding a mention about those changes in the RN of 4.3 is better now than never, Marius, could you take care of it ? Thanks for your attention, -- Denis Gervalle SOFTEC sa - CEO eGuilde sarl - CTO