I am trying to do migration. I am using 7.9 version. engines start up and search

If you're starting with a clean primary database you should delete the keystore and let it get generated on first startup.

As per the error log it seems that the keystore file is present and it is not deleted, but it seems that the issue is related to password.

I would suggest you to delete the keystore file from <Appian_Home>/_admin/shared. Drop the schema again and create a new one and then check.

i deleted the keystore file and dropped the primary and started again...but still getting this error mentioned below:

ERROR [org.apache.catalina.core.ContainerBase.[jboss.web].[default-host].[/suite]] (ServerService Thread Pool -- 132) JBWEB000287: Exception sending context initialized event to listener instance of class com.appiancorp.common.config.ConfigurationLoader: com.appiancorp.common.config.FatalConfigurationException: com.appiancorp.suiteapi.common.exceptions.AppianException: The internal encryption module is in an inconsistent state. The keystore password is not present in the primary data source. If migrating or restoring from backup, ensure that the primary data source contains all of the tables and data. (APNX-1-4210-004)

If you are performing a migration from an earlier Appian version versus a clean install, I don't think you should be dropping the Primary DB. Would it not cause the KDBs and primary db to be out of sync?

I did delete like 4 or 5 versions of kdb's so that it should have gone to the beginning instance of it.....but the problem is keystore file is not getting generated. I have previously deleted the primary db and started over again and was successful. But this time don't know what's causing the problem. The primary db tables get generated but the keystore file doesn't. the problem happened because I automated the migration by writing a batch file to copy kdb's and other files using commands like xcopy and I noticed that after copying all kdb files that I copied were of 0KB and so I deleted them and then I ran cleanup.bat several times so that it should have gone to the beginning instance.....

What I recommend is re-copying the keystore file from the old environment or even better:

1. Re-install Appian
2. Re-migrate the old environment following the migration guide (not that you do have to copy the keystore from the old environment to the new one)
3. Test again

It's not safe to continue to use the environment after so many deletions. The keystore is not being re-created because the Primary DS already knows it was created. There's a way to force it to be re-created but since this environment has clearly experienced multiple wrong attempts to migrate I definitely don't recommend using it.