I wonder if an AutoCAD plugin can be built for that. If those files exist then it should present the read only prompt even if access to the dwg file appears to be unrestricted. A potential fix would be to add logic to AutoCAD to check for the existence of the dwl and dwl2 files as part of its lock procedure. There appears to be a disconnect as that information is not transferred to the Google File Stream. If the flag is used the operating system is made aware and any future attempts cause the prompt. This would explain why if TestUser1 tries to open the dwg twice on the local system they get the expected read only prompt. More on the openfile function can be found here: In the definition of the OpenFile function in winapi you can specify how the file is opened with the following flags: OF_SHARE_COMPAT, OF_SHARE_DENY_NONE, OF_SHARE_DENY_READ, OF_SHARE_DENY_WRITE, and OF_SHARE_EXCLUSIVE I suspect that since Autocad is running on windows and written in C it may be using winapi to open files. This is a really good article on file locking: Although the locking is ultimately performed by the file system, it is the responsibility of the application to perform the lock. Thanks for the response and have done a bit more research. I wonder if its possible for the file check to be performed as an operation separate from the creation of the lock files.

I think because Google File Stream allows two users to create files with the same name it doesn't generate the file exist error AutoCAD is expecting. I think it may attempt to create the lock files and then if it gets a file exist error it reads the contents of the file. I think it may be how the test for the existence of the lock files is performed. Would love to know if this can be resolved. In Google Drive there are two sets of lock files(dwl and dwl2) one set for TestUser1 and one set for TestUser2. New lock files are created for TestUser2. However if TestUser2 attempts to open the dwg file on their computer the two lock files(dwl and dwl2) that were created when TestUser1 opened it are not read. If TestUser1 attempts to open the dwg file again on their local computer they get the expected read only prompt. The process creates the two lock files(dwl and dwl2). TestUser1 opens the dwg file on the Google File Stream Team Share. We have two user: TestUser1 and TestUser2. However the files don't appear to be read if another user opens the dwg file. These files get created on the google file stream drive appropriately. So I know that the dwl and dwl2 files are created as part of the dwg file locking process.

Autocad 2018 dwl dwl2 open file