Why was the Avestan script developed?

The Avestan script was developed by Zoroastrian priests to address the limitations of the Pahlavi script when recording the Avesta, the sacred scripture of Zoroastrianism.1

By the time the Avestan canon was being fixed between the 4th and 6th centuries CE, Avestan had long ceased to be a spoken language and was preserved only through oral tradition by the priesthood. The Pahlavi script, which had evolved from Aramaic, was considered inadequate for this task because it was highly ambiguous; it had reduced the original 22 Aramaic letters to 14, which were further obscured by numerous ligatures.231

To ensure the precise recording of the traditional pronunciation of their sacred texts, priests devised the elaborate Avestan script. This system utilized 48 distinct letters, created through the differentiation of the 14 characters used in Pahlavi, providing the phonetic accuracy necessary to preserve the ancient language.1