Do not write down anything from me, and he who wrote down anything from me except the Qur'an, he should erase it. But, narrate from me, for there is nothing wrong in doing so. Whoever attributes any falsehood to me, let him occupy his seat in Hellfire

The Prophet (may Allah's peace and blessings be upon him) forbade his Companions to write anything from him, and ordered anyone who wrote anything, other than the Qur'an, to erase it. Then, he allowed them to narrate from him without incurring sin in doing so. However, they have to be truthful in what they transmit from him. He also warned that whoever tells a lie intentionally about him, his punishment is Hellfire.
The prohibition to write Hadīth was later abrogated, for the Prophet (may Allah's peace and blessings be upon him) forbade it at an earlier time. But later on, when the Hadīths became numerous, and some of them might not be kept to memory, the Prophet (may Allah's peace and blessings be upon him) allowed writing them down. In this respect, he said in his sermon: ''Write for Abu Shāh'' when Abu Shāh asked for a written record. The Prophet (may Allah's peace and blessings be upon him) also allowed ‘Abdullāh ibn ‘Amr to write. He also commanded his Ummah to convey knowledge, which if not written, will be lost.
The prohibition in the Hadīth in hand is said to refer to the writing of Hadīth along with the Qur'an in the same scroll; or that it is specific to the time when the Qur'an was being revealed, so that it would not be confused with something else. Then the writing was later allowed.
The first probability, i.e. abrogation, is more preponderant.