@alanwilky47: Please try pressing the Volume Down and Power buttons together for around 10 seconds until your S21 Ultra restarts, as this will refresh the device and address any issues that might be affecting the Camera app. Following the restart, open the Camera app and check your front and rear cameras to see if the issue persists. If it does, please head to the Phone app, dial *#0*# into the telephone keypad and select Megacam and Front Cam from the series of grey tiles. If the same 'Camera failed' message appears then the issue is likely to be hardware related, in which case please head to samsung.com > Scroll to the bottom of the page > Contact us, and get in touch via your preferred contact option, and an advisor will be able to arrange an engineer's inspection under warranty.
I have the same problem with both my front and rear camera on my S21 Ultra.
Initially i got the 'camera failed' message with the front only but now both have stopped working.
I took the device in to a local shop to get the cameras changed but was told that they are fine and i have since tried the star,hash,zero,star,hash which showed the front camera was still not working but the rear camera worked.
Is there a software fix for this?