What type of password I have to give to set the custom account for application pool identity

Getting Error - The specified password is invalid.Type a new password.

Use the below command from the CMD and it will fix the issue-

%windir%\system32\inetsrv\appcmd.exe set config /section:applicationPools /[name='APP_POOL_NAME'].processModel.identityType:SpecificUser /[name='APP_POOL_NAME'].processModel.userName:DOMAIN\USER_NAME /[name='APP_POOL_NAME'].processModel.password:PASSWORD

For me, it was that the domain user had to be a member of the IIS_IUSRS group. Added the user to the group via Computer Management -> Users and Groups, restarted the app pool and all was well.

For me it was in my haste to follow the instructions for creating a merge agent account for replication I had left "User must change password at next logon" ticked. Make sure that the user does't have this ticked.

If you are using a gMSA service account you have to enter domani\account$, meaning add a dollar sign at the end of your username.

Use Your Laptop Password it worked for me.