Sentinel 2 mosaicing

Hi,
I am trying to mosaic sentinel-2 images after resampling but i get the following error

I resampled to 60 m and the bands I require are B11, B8A and B3

Does anyone know why is this happening?

Regards,
Bhuwan

It would be good if you could provide some more information to us.
The log file would be helpful. With the log file we can see where the exception is thrown.
Maybe you can see already the detailed information when you click on the red stop sign in the lower right corner after the error occurred. The stack trace shown there is already helpful.
You can find the log file in <user_dir>\AppData\Roaminig\SNAP\var\log

Thank you very much… the problem was solved… I used Qgis for some steps.