Just tried an upgrade from 3.1.3. Uploaded all files, upgrade xml, got this message:
Callback Tinhte_XenTag_Listener::template_create is invalid (Invalid Method).
EDIT: Tried upgrade xml again and it seemed to have worked. Your addon is great but it's the only one that exhibits problems that can only be resolved by repeating upgrades so not sure what you're doing but maybe double check it.
I spoke too soon.
This is what I get when I insert a post tag.
Mysqli prepare error: You have an error in your SQL syntax; check the manual that corresponds to your MariaDB server version for the right syntax to use near ') AND (tag_watch.send_alert <> 0 OR tag_watch.send_email <> 0)' at line 23
Zend_Db_Statement_Mysqli->_prepare() in Zend/Db/Statement.php at line 115
Zend_Db_Statement->__construct() in Zend/Db/Adapter/Mysqli.php at line 381
Zend_Db_Adapter_Mysqli->prepare() in Zend/Db/Adapter/Abstract.php at line 478
Zend_Db_Adapter_Abstract->query() in XenForo/Model.php at line 219
XenForo_Model->fetchAllKeyed() in Tinhte/XenTag/Model/TagWatch.php at line 202
Tinhte_XenTag_Model_TagWatch->getUsersWatchingTags() in XenCentral/MultiSite/Model/XenTag/TagWatch.php at line 29
XenCentral_MultiSite_Model_XenTag_TagWatch->getUsersWatchingTags() in Tinhte/XenTag/Model/TagWatch.php at line 58
Tinhte_XenTag_Model_TagWatch->sendNotificationToWatchUsersOnTagged() in Tinhte/XenTag/XenForo/TagHandler/Tagger.php at line 126
Tinhte_XenTag_XenForo_TagHandler_Tagger->save() in Tinhte/XenTag/XenForo/DataWriter/DiscussionMessage/Post.php at line 17
Tinhte_XenTag_XenForo_DataWriter_DiscussionMessage_Post->_postSaveAfterTransaction() in bdTagMe/XenForo/DataWriter/DiscussionMessage/Post.php at line 13
bdTagMe_XenForo_DataWriter_DiscussionMessage_Post->_postSaveAfterTransaction() in XenForo/DataWriter.php at line 1423
XenForo_DataWriter->save() in XenForo/ControllerPublic/Thread.php at line 557
XenForo_ControllerPublic_Thread->actionAddReply() in XenForo/FrontController.php at line 347
XenForo_FrontController->dispatch() in XenForo/FrontController.php at line 134
XenForo_FrontController->run() in /var/www/site.com/htdocs/index.php at line 13