Running Unraid 7.1.2.

System was fine, I just got new hard drives and wanted to add them. Popped a 24TB into a free slot and ran a preclear on it.

Stopped the array, expanded it by one slot, moved my old parity drive (22 TB) into the new slot and the new 24TB into the parity slot. Tried to start the array but got an error saying "Can't add and remove disks at the same time".

Now my array is stuck. I have an error saying "Too many wrong and/or missing disks!" next to a greyed out Start button for the array, but I can't change my array settings at all because the drives are not visible on the WebGUI. I assume they are still there, there are just blank rows.

Refreshing and force refreshing didn't work. Trying another browser didn't work.

Tried to get diagnostics, but it seemed to hang. The terminal button isn't responsive so I can't get into CLI.

Edited July 11, 2025Jul 11 by Dinhternet

Try booting in safe mode.

If you haven’t update the unraid connect plugin as it’s known to do this to the disk page.

If safe mode works, it’s probably the connect plugin

2 hours ago, Dinhternet said:

but got an error saying "Can't add and remove disks at the same time".

You have to split what you want to do into two steps.

Easiest thing to do would be to move the old parity to the new slot and start the array leaving parity unassigned. After starting the array immediately stop it and assign the parity and start the array to build new parity based on the new disk set. The downside to this is that the array is unprotected until the parity rebuild.

An alternative is to not immediately assign the old parity to the array but simply assign the new 24tb parity drive and start the array to begin the parity rebuild. Keep the old parity drive intact as this gives a reversion path if a disk fails when rebuilding the near parity. After this completes successfully then you add the old parity drive to a new slot and array will add it and start clearing the drive, and when that completes you can format the drive to start using it.

If you were not adding the old parity drive to a new slot but instead using it to replace an existing drive then the Parity Swap procedure would allow this to be combined with upgrading parity.