An issue with a client has arisen which I've never seen before and can't find the explanation for. The solution has a user interface file and a suite of data files. After years of running peer-to-peer I finally got them onto FileMaker Server 13 last year and the system has been running successfully since then. At the beginning of this year a script detects the new year and resets a number field in a single record utility table in the interface file with the new year, which is used to prefix the serial number field in the main data table. This script has worked faultlessly for some years, but failed this year on FMS. The value in the number field in the interface file didn't get changed with the script. I had the client try to manually edit the field but she got a message saying the file was read only. That's the crux of the problem. Why is it read only? In Windows Explorer, 'Read only' in Properties is unchecked. My copy of the files, running locally on my Mac, are OK - the number field was changed as expected when the script ran at the beginning of the year. The only difference is that the client's files are running on FMS.
The files were uploaded to FMS initially in Windows Explorer. The fact that the interface file was read only wasn't noticed because, normally, no data is ever written to this file. All data files are OK because data entry has been occurring successfully. I got the client to upload a copy of the interface file through FileMaker's File>Sharing menu in case it was the copy process in Windows Explorer, but that made no change.
So, my question is, what can cause one file to go read only?