There are several saints and blesseds named Bertha so you need to be more specific.
St. Clare of Assisi was canonized on September 26, 1255, by Pope Alexander IV.
St. Etheldreda was canonized by Pope Celestine III in 1198.
Catherine was canonized in July of 1461 by Pope Pius II.
Pope Pius XI canonized More in 1935
Maria Goretti was canonized by Pope Pius XII.
St. Eligius was canonized in the Pre-Congregation era. This was when people were often canonized because of their popularity while they were alive.
If you are referring to St. Francis of Assisi he was canonized on July 16, 1228, by Pope Gregory IX.
King St. Louis IX was canonized in the year 1297 by Pope Boniface VIII. Exact day unknown.
St. Benedict was canonized in the year 1220 by Pope Honorius III.
He was canonized on June 29,1867, by Blessed Pope Pius IX.
Saint Bertha of Avenay was declared a saint by the early Catholic Church, probably by a bishop, long before the canonization process was initiated, probably in the 7th or 8th century.
She was canonized on May 24, 1925, by Pope Pius XI, in Rome.