The King of Egypt had a dream that Allah the Exalted made a reason for Yusuf's release from prison, with his honor and reputation preserved. When the king had this dream, he was astonished and fearful and sought its interpretation. He gathered the priests, the chiefs of his state and the princes and told them what he had seen in a dream, asking them to interpret it for him. They did not know its interpretation and as an excuse, they said,
(and we are not skilled in the interpretation of dreams.) They said, had your dream been a vision rather than a mixed up false dream, we would not have known its interpretation. The man who was saved from the two, who were Yusuf's companions in prison, remembered. Shaytan plotted to make him forget the request of Yusuf, to mention his story to the king. Now, years later, he remembered after forgetfulness and said to the king and his entourage,
After that, say the verses cited above, Allah Ta` ala created through the workings of what is unseen (Al-Ghayb), a particular way out for the release of Sayyidna Yusuf (علیہ السلام) . This made the king of Egypt see a dream which caused him great anxiety. He assembled the known dream interpreters and soothsayers of his state and asked them to interpret his dream. None of them could understand the dream. The answer they all gave was: أَضْغَاثُ أَحْلَامٍ ۖ وَمَا نَحْنُ بِتَأْوِيلِ الْأَحْلَامِ بِعَالِمِينَ : ' (It seems to be) a mishmash of dreams, and we do not know the interpretation of dreams.' The word: أَضْغَاثُ (adghath) is the plural form of: ضِغث (dighth) which literally refers to a bundle of chaff or husk separated from grain while threshing and is a collection of different kinds of waste material. The sense of their saying was that this dream was somewhat muddled, confused and an admixture of many thoughts and things, and they did not know how to interpret such dreams. Had it been a regular dream, they would have had interpreted it.
Tazkirul Quran
Maulana Wahiduddin KhanOn ayahs 42–44
Of the two youths who were put in jail, one was a bread maker and the other was a wine-server to the king of Egypt. Both were accused of trying to poison the food of the king. On investigation, the wine-server proved to be innocent of the allegation. He was released from the jail and was again appointed as a wine-server to the king. His dream meant that he was serving wine to the king in dream and after few days he would really serve wine while awake. The bread maker was proved guilty. He was hanged and left for the birds to peck at his body and, in this way, be a lesson to the people. Both the interpretations of Joseph proved to be correct but, after reaching the palace, the wine-server forgot to mention Joseph to the king as promised. He remembered his promise only when the king had a dream and asked his courtiers to interpret it.
Uthmani text of the Madinah mushaf (King Fahd Complex). Translation: Saheeh International. Tafsir via Quran.com.