Ensure you have (the last version for 1.5.6). Newer SMAPI builds will not work. Download SMAPI for 1.5.6 from the official SMAPI GitHub releases page.
Steam makes it harder to stay on an old version, but it is possible using the beta branches feature.
In the "Extras" section of the game page, look for .
To ensure smooth gameplay, make sure your PC meets the minimum system requirements:
Many players prefer version 1.5.6 because certain older mods may not yet be compatible with the massive 1.6 update. Right-click Stardew Valley in your Library. Properties In the "Beta Participation" dropdown, select legacy_1.5.6