Affirm_Affirm
Open app/code/community/Affirm/Affirm/etc/config.xml
and find following lines:
<customer_login>
<observers>
<affirm_affirm_mfp_detection_customer_login>
<type>singleton</type>
<class>affirm/order_observer_mfp_updateOnCustomerLogin</class>
<method>execute</method>
</affirm_affirm_mfp_detection_customer_login>
</observers>
</customer_login>
Replace them with:
<customer_login>
<observers>
<affirm_affirm_mfp_detection_customer_login>
<type>singleton</type>
<class>affirm/order_observer_mfp_updateOnCustomerLogin</class>
<method>execute</method>
</affirm_affirm_mfp_detection_customer_login>
</observers>
</customer_login>
<controller_action_postdispatch_firecheckout_index_saveOrder>
<observers>
<affirm_checkoutbutton_proceed>
<type>singleton</type>
<class>affirm/order_observer_applyAffirmPaymentMethod</class>
<method>execute</method>
</affirm_checkoutbutton_proceed>
<controller_action_postdispatch_affirm_payment_confirm>
<type>singleton</type>
<class>affirm/order_observer_afterSaveOrder</class>
<method>postDispatchSaveOrder</method>
</controller_action_postdispatch_affirm_payment_confirm>
</observers>
</controller_action_postdispatch_firecheckout_index_saveOrder>
Save the file and clear Magento cache.