Here are the three safest methods:

To prevent your game from automatically updating to newer versions in the future, you can create a "portable" copy: Ultimate Guide: Modding Stardew Valley 1.6 PC!

Steam allows you to "roll back" to version 1.5.6 easily using the built-in legacy branch: Open your and right-click on Stardew Valley . Select Properties from the dropdown menu. Click on the Betas tab on the left. In the "Beta Participation" dropdown, select legacy_1.5.6 .

as of late 2024) or "rolling back" to the specific 1.5.6 version for mod compatibility 1. How to Download the Latest Version