Is it obligatory to inform the questioner of a change in juristic opinion after providing an answer with evidence, when another preponderant opinion subsequently becomes clear?

"Scholars have differed on the issue of the necessity of informing the questioner about a change in the mufti's juristic opinion (ijtihad). Ibn al-Qayyim preferred a detailed approach: if the error in the first fatwa contradicted a clear text from the Qur'an or Sunnah that has no counter-evidence, or contradicted a consensus (ijma'), then it is obligatory to inform the questioner. However, if the error was merely a contradiction of the mufti's own madhhab or the text of his imam, then it is not obligatory to inform the questioner. This detail applies to the mujtahid scholar. But if the mufti issued a fatwa without knowledge or ijtihad, and then came to know the correct opinion, he is obligated to inform the questioner. Furthermore, the mufti must be knowledgeable of the sayings of the people of knowledge and the legal evidences, and he should not issue fatwas based on conjecture or blind imitation except when necessary."