Rejected RRC connection reestablishment without UE contexts higher

I have a number of rejected RRC connection reestablishment without UE contexts higher?
Do you know the cause for this problem?

Any impact on RRC success rate?

I have the number of RRC connection setup failures cause no reply high.

Is this after the HO?
eNBs need to exchange UE contexts or MME needs to transfer this during HOs.
See if there are any issues on X2 or at MME.

How you check that, please?

Check on MME, there should be some counters to check this.
Check X2 configuration.

There is feature X2 based RLF, check it’s true or not.
As you mentioned RRC connection reestablishment there without UE context.
So in your case UE sending RRC connection reestablishment request on source cell only.
In case of X2 based RLF UE context need to transfer to target.