No key with alias found in keystore

The problem seems to be with the wrongly spelled key alias
In my case the alias should have been toyanath patro where I wrongly tried to use toyanathpatro . So the best suggestion would be:

1. Don’t use space or invisible character in the key alias. as far as possible

2. There is a small selection button (3 horizontal dots) on the right side of key alias editable field. Use that button to find the alias which resides in that signature file.