Mistakes of Shaykh al Islam Ibn Taymiyyah as per Ibn Hajr asqalani and Ibn Kathir.
Ibn Hajr al Asqalani said regarding Ibn Taymiyah:
وَمَعَ ذَلِك فَهُوَ بشر يُخطئ ويصيب فَالَّذِي اصاب فِيهِ وَهُوَ الْأَكْثَر يُسْتَفَاد مِنْهُ
Along with that he was a human being who made mistakes and got things right. AND MOST OF TIMES HE IS CORRECT AND CAN BE benefited from. [Taqreez Ibn Hajar on Radd al Wafir]
Ibn Kathir said:
وبالجملة كان رحمه الله من كبار العلماء وممن يخطئ ويصيب ولكن خطأه بالنسبة إلى صوابه كنقطة في بحر لجي، وخطأه أيضاً مغفور له كما في (صحيح البخاري):
((إذا اجتهد الحاكم فأصاب فله أجراً وإذا اجتهد فأخطأ فله أجر)) فهو مأجور.
وقال الإمام مالك بن أنس: كل أحد يؤخذ من قوله ويترك إلا صاحب هذا القبر.
As a whole he Rahimah ullah was among the great scholars and among those who makes mistake and are right also. But his mistakes against him on being right is like a drop of water in a vast deep sea, and his mistake is also forgiven as it is mentioned in Saheeh al Bukhari “”When a judge gives judgement and strives to know a ruling (ijtahada) and is correct, he has two rewards. If he gives judgement and strives to know a ruling, but is wrong, he has one reward” So he (Ibn Taymiyyah) will be rewarded. and Maalik bin Anas said: ‘Take and leave the words of all men, except the one in this grave,’ pointing towards the grave of Allah’s Messenger (sallalalhu alaihi wa-sallam). [al Bidaya wal Nihaya 14/162]