The Central Bank of Nigeria CBN has stopped the electronic transfer of cash deposits held in domicillary bank accounts in Nigeria.
In a circular released by the central bank, the bank said that only funds that were transferred electronically into an account can be transferred out electronically. All funds paid in as cash can only be transferred electronically if the amount does not exceed the $10,000.
See letter:

It is not immediately clear what the rationale behind this latest policy is but analysts immediately think it will further create pressure on an already unstable economy.
The CBN had earlier tweeted a clarification of the policy on the official handle which seemed to state an outright ban
Only transfers into domiciliary accounts can be transferred from such accounts while cash deposits into such accounts can only be withdrawn in cash
— Central Bank of Nigeria (@cenbank) February 22, 2020