Issue description
Archicad may not be able to save a project correctly if the project file is located in a folder that is synchronized by a cloud storage, file hosting, backup, or file synchronization service. (This includes services such as Dropbox, Google Drive, Microsoft OneDrive, iCloud Drive, Box, SharePoint, or similar tools.)
On very rare occasions, saving Archicad project files directly inside a synchronized folder may result in data loss or file corruption.
Note: BIMcloud operation is also affected by synchronization utilities. It is not recommended to synchronize BIMcloud content with such services.
Explanation
Archicad's Save function is a complex process that involves generating temporary and lock files and performing extensive disk read and write operations.
Most synchronization clients do not wait for the save process to finish before reacting to file changes. Instead, they may begin uploading, downloading, scanning, locking, renaming, or replacing files as soon as a change is detected in a monitored folder.
While the synchronization client is processing these file changes, Archicad may still be completing the save operation. This can interfere with the project file save sequence and may prevent Archicad from saving the file successfully.
Solution
Avoid saving Archicad project files directly in a folder monitored by a cloud storage synchronization utility.
If you need to save active project files to such services, it is recommended to use a third-party utility that supports local file and folder copying or scheduled synchronization. This allows you to schedule a folder synchronization task between your Archicad project folder and a backup folder within the monitored folder of a file hosting service, preferably at times when you are not actively working on the project.
There are many third-party applications for such tasks. For example, the open-source FreeFileSync application is quite popular and supports such workflows.
If you choose to save directly to a monitored folder, make sure the synchronization utility provides an option to disable real-time monitoring, syncing, or file scanning. Disable these features before saving Archicad files, then re-enable them only after the save operation is complete.