Your Project Zomboid settings will not save

If a setting will not save, read what the panel says next to it. There are four usual reasons: the server is running (for the two editors), the value is outside what is allowed, the row is read only, or your role does not allow changing settings.

The editors: Server Settings and Sandbox Settings

• The server is running. The notice Stop the server to change these settings is shown and the save buttons are off. Click Stop, wait for Offline, then change and click Save only or Save & start.
• A value is out of range. The editor names the setting and says "must be between a and b" or shows "This value is outside the range the file allows". Change the number.
• The Forced spawn point is not in the right form. It must be three whole numbers, x,y,z, or 0,0,0: How to set a spawn point on your Project Zomboid server.
• The editor says the file is from a different build or not laid out the way the game writes it. Edit it under Files: Project Zomboid Sandbox Settings says the file is from a different build.
• A setting is missing. The editors show a setting only when the game's file has it. Start the server once so the game writes the file.

Game Settings

• Max Players and RCON Port are Read only. Use Edit slots for players: How to change player slots on your Project Zomboid server.
• The panel refuses the value. The row keeps the old value and shows the reason. Common rules: Server Name takes letters and digits only, up to 64. Admin Username takes up to 20 characters and no spaces, quotes, backslashes, asterisks or question marks. Admin Password and RCON Password take 6 to 32 characters without double quotes or backslashes. Workshop Mod IDs take names with letters, digits and _ . - separated by semicolons: a title with spaces is refused.
• Text rows save when you leave the field. Click outside the box or press Enter.
• It saved but nothing changed. Settings apply at the next start: click Restart now.

Your role

A helper needs the permission to update settings. If the rows are greyed out for you, ask the server owner: How to invite friends and give them access to your server.

Still stuck

Open a ticket with the name of the setting and the exact message. See also Your Project Zomboid settings keep changing back.