You probably turned off or rebooted your system while Wayfarer was still writing. The shut down indicator window may be closed, but the file system is still writing data to disk. Use the HDD indicator light before shutting down the system.

Even if the common sense is that you could turn off Amigas at any time, is simply wrong. Amigas and therefor MorphOS have no virtual memory and so far less HDD activity, but when there is a write, then there is a write you should not interrupt.

Cache files are normal files and have nothing to do with file system failures of any kind. Wayfarer is just writing a lot of data during operation.