Command failed fastboot: error: Device does not support slots

Pixel 4a Android 11 Sunfish custom build no valid slot to boot error fastboot_ error_ failed to identify current slot Proceed with the instructions on screen 4 If you are unable to locate or find the Service Tag, click the Product Category of your computer 5 Choose the fastboot_ error_ failed to identify current slot I have total 3 slots but only using 1 SSD of 256 gb and 1 HDD of 1 TB , the slot which I'm not using can accommodate another SSD I guess

fastboot getvar currentslot In boota get fastboot lock status error c:1341: ERROR: Error verifying slot _a with result ERROR_INVALID_METADATA