Chain halts after runtime upgrade | Getting Ignoring empty epoch change. Error with block built on

[ashi20192020]

Is there an existing issue?

• I have searched the existing issues

Experiencing problems? Have you tried our Stack Exchange first?

• This is not a support question.

Description of bug

I have a solo chain using Babe consensus. In my new branch, I implemented OneSessionHandler in one of my pallets. I am using this to collect active validators.

It's working fine if I run chain with my new branch. But if I do runtime upgrade on main branch, I started getting below error when new session changes:

2024-07-18 15:46:12 Corrupted state at `[206, 197, 7, 13, 96, 157, 211, 73, 127, 114, 189, 224, 127, 201, 107, 160, 224, 205, 208, 98, 230, 234, 242, 66, 149, 173, 76, 207, 196, 29, 70, 9]: Error`    
2024-07-18 15:46:12 Ignoring empty epoch change.    
2024-07-18 15:46:12 🎁 Prepared block for proposing at 34 (0 ms) [hash: 0xfe09b1a95631607aebada259e1a6adde43c64f4162e7fc33ae7468f42582157b; parent_hash: 0x4194…62e8; extrinsics (1): [0x6084…214a]    
2024-07-18 15:46:12 🔖 Pre-sealed block for proposal at 34. Hash now 0x73c962d1c74905a331ec6f81ce6bad5abf20d3bffc428846c3b8a43698d2dfcb, previously 0xfe09b1a95631607aebada259e1a6adde43c64f4162e7fc33ae7468f42582157b.    
2024-07-18 15:46:12 Error with block built on 0x419470202271cf7ba8e482c437226dc3201627ac9a7890f420b25506103162e8: Import failed: Expected epoch change to happen at 0x73c962d1c74905a331ec6f81ce6bad5abf20d3bffc428846c3b8a43698d2dfcb, s286882962    
^

After above error, chain stops producing blocks.

Here is my OneSessionHandler implementation:

impl<T: Config> sp_application_crypto::BoundToRuntimeAppPublic for Pallet<T> {
		type Public = T::AuthorityId;
	}

	impl<T: Config> OneSessionHandler<T::AccountId> for Pallet<T> {
		type Key = T::AuthorityId;

		fn on_genesis_session<'a, I: 'a>(validators: I)
		where
			I: Iterator<Item = (&'a T::AccountId, Self::Key)>,
		{
			let validators = validators
				.map(|(_, k)| T::AccountId::decode(&mut &k.into().encode()[..]).unwrap())
				.collect::<Vec<_>>();

			ValidatorSet::<T>::put(validators); 
		}

		fn on_new_session<'a, I: 'a>(_changed: bool, validators: I, _queued_authorities: I)
		where
			I: Iterator<Item = (&'a T::AccountId, Self::Key)>,
		{
			let validators = validators
				.map(|(_, k)| T::AccountId::decode(&mut &k.into().encode()[..]).unwrap())
				.collect::<Vec<_>>();
			ValidatorSet::<T>::put(validators);
		}

		fn on_disabled(_i: u32) {}
	}
}

I also added corresponding changes in runtime.

impl_opaque_keys! {
	pub struct SessionKeys {
		pub grandpa: Grandpa,
		pub babe: Babe,
		pub im_online: ImOnline,
		pub authority_discovery: AuthorityDiscovery,
		pub template_module: TemplateModule,
	}
}

I haven't made any change related to epoch. Also if I remove last key from above SessionKeys, then it works fine but it does not call on_new_session method of OneSessionHandler.

Can somebody please help to fix this?

Steps to reproduce

No response