Western countries are withdrawing their Embassies staff from Eritrea
Tigrai Online April 24, 2020
It is not clear what is going on in Eritrea, but many countries including United Kingdom and the U.S.A are evacuating their staff members from their Embassies in Asmara, Eritrea.
The reason given by the UK Embassy simply says "given the rapidly changing situation..." as you can see in the following paragraph.
"Given the rapidly changing situation in Eritrea we are temporarily withdrawing all UK staff from our Embassy. The Embassy will continue to carry out essential work including providing 24/7 consular assistance and support to British nationals in Eritrea. Removal of information about a flight which departed Eritrea on 18 April. ('Summary' and 'Return to UK' pages)"
Here is the UK foreign travel advice, read more