Mandarin equivalent of 轉行 (zyun3 hong4), which means to switch industries?
First: 《广州话-普通话》 indicates that 转行 is


  粤


Cantonese. This has probably changed since it was published but they also give the Mandarin equivalents:


  改行；转业


《广州话方言词典》 also gives the same two Mandarin equivalent words, in opposite order:


  转业；改行


改行 is probably the most colloquial option.