I don't have a backup program that I use. I also stopped Windows's own shares. It gives the same error again. I copied it to My Documents folder in C. There the result is the same. I right clicked the project folder and removed the Read Only property for all files. I have given Full Control in the security settings. I uninstalled and reinstalled B4A. The problem is not solved. What else do I need to check? When I delete the Objects folder it does the build. Therefore, it is as if there is no writing problem, no access problem. But it looks like the error.