The following compatibility issues have been identified with CB 1.9.1 compatible plugins when upgrading from CB 1.9.1 to CB 2.0:

1. CB Activity 2.4.1 module and plugin is built for old CB Blogs

This means that CB Activity will not work at all on CB 2.0 and needs a quick update.
If someone has CB Activity running on a CB 1.9.1 site and upgrades to CB 2.0, then the CB Activity module must be unpublished and the plugin also, otherwise the site will break.

Solution is to release a new CB Activity package for CB 2.0.

Compatibility fix (making CB Activity not failing) will be added to CB 2.0 RC2. A new CB Activity package will still be needed to record the new integrated Blog.

2. CBSubs GPL 3.0 plugin will produce following error on CB 2.0:

Fatal error: Declaration of cbpaidTimed::get() must be compatible with CBLib\Database\Table\TableInterface::get($var, $def = NULL) in /Users/nick/Documents/JOOMLAPOLIS/DEV/SITES/J333CB20RCALLUPGRADE/components/com_comprofiler/plugin/user/plug_cbpaidsubscriptions/models/misc/cbpaidTimed.php on line 500

the issue of CBSubs "Declaration of cbpaidTimed::get() must be compatible with CBLib\Database\Table\TableInterface::get" can't be fixed in core CB. That needs a new CBSubs release

Compatibility fix will be added to CB 2.0 RC2.

3. CB Password Strength field 1.0.1 will produce the following error after upgrading to CB 2.0:

Fatal error: Cannot access protected property CB\Database\Table\FieldTable::$_db in components\com_comprofiler\plugin\user\plug_cbpasswordstrength\cbpasswordstrength.php on line 20

Warning: array_keys() expects parameter 1 to be array, null given in libraries\CBLib\CB\Legacy\cbPluginHandler.php on line 1057

Warning: Invalid argument supplied for foreach() in libraries\CBLib\CB\Legacy\cbPluginHandler.php on line 1057

Solution is to unpublish this plugin from the CB Plugin Manager as similar functionality is now built in CB 2.0.

Automated upgrading will be added to CB 2.0 RC2.

4. UddeIM's own CB Plugin

Subject : Fatal error: Call to undefined method getuddeimTab::cbPMSHandler() in ...

Compatibility fix will be added to CB 2.0 RC2.
Temporary Solution is to unpublish this plugin from the CB Plugin Manager.

5. GroupJive 2.7.0 gives 0 Serialization of 'Closure' is not allowed with CB 2.0 RC

This bug will be addressed in CB 2.0 RC2

6. Installation of CB 1.9.1 plugins on CB 2.0 environment fails with

Fatal error: Class 'HTML_comprofiler' not found in /..../libraries/CBLib/CB/Legacy/cbInstallerPlugin.php on line 357

This bug will be fixed in CB 2.0 RC2