Contradiction with Deuteronomy 28:15
This verse outlines curses and hardships for disobedience, whereas Zechariah 8:11 speaks of God not dealing harshly with the remnants.
Deuteronomy 28:15: But it shall come to pass, if thou wilt not hearken unto the voice of the LORD thy God, to observe to do all his commandments and his statutes which I command thee this day; that all these curses shall come upon thee, and overtake thee:
Contradiction with Lamentations 3:31-33
Lamentations highlights God's inevitable compassion after affliction, while Zechariah 8:11 speaks of a changed approach without affliction.
Lamentations 3:31-33: For the Lord will not cast off for ever:
Contradiction with Amos 9:8
This verse speaks of destruction upon the sinful kingdom, whereas Zechariah 8:11 indicates a time of relenting and favor.
Amos 9:8: Behold, the eyes of the Lord GOD [are] upon the sinful kingdom, and I will destroy it from off the face of the earth; saving that I will not utterly destroy the house of Jacob, saith the LORD.