The Usage FAQ has solutions to most issues, please search through it for your issue and follow the General Troubleshooting Steps: https://github.com/tModLoader/tModLoader/wiki/Basic-tModLoader-Usage-FAQ
Some things not in the FAQ above can be found in this flowchart. Click on the link or "Open Original" to see the image in full resolution:
https://i.imgur.com/ChkZpD0.png
https://github.com/tModLoader/tModLoader/wiki/Basic-tModLoader-Usage-FAQ#controlled-folder-accessUnauthorizedAccessException:
https://github.com/tModLoader/tModLoader/wiki/Basic-tModLoader-Usage-FAQ#systemunauthorizedaccessexception-access-to-the-path-is-deniedMigrate Everything From 1.3 to 1.4:
https://github.com/tModLoader/tModLoader/wiki/tModLoader-guide-for-players#migrate-everything-from-13-to-14
I've made a build of tModLoader that might help us identify this issue, if you want to give it a try, please visit and read https://discord.com/channels/103110554649894912/1216931304709427242
If you see the following error, disable the TerrariaAmbiance mod.
System.NullReferenceException: Object reference not set to an instance of an object.
at Microsoft.Xna.Framework.Audio.SoundEffect.Dispose()
If you see tiles that look like they aren't adapting to their neighbors as they should, your issue is likely the Nitrate mod.
Check C:\Program Files (x86)\Steam\steamapps\common\tModLoader\dotnet\shared\Microsoft.NETCore.App\8.0.0 folder, make sure it has 184 items in it. If it doesn't, your antivirus might have quarantined some files or the dotnet install was incomplete for some reason. Delete the dotnet folder and try launching again.
In Steam right click on tModLoader in the library, then hover overManageand click onBrowse local files. In the folder that appears findtModLoader-Logsand open that folder. Inside that folder are the logs files. Select them all except the Old folder and drag them into your thread. If you need a visual guide to this process watch this: https://user-images.githubusercontent.com/4522492/265850016-3f4efa43-753f-4733-b630-ba85e711340c.mp4
ManageBrowse local filestModLoader-Logs