famous Backend error. 400 Bad Request starting from yesterday

The api works fine until yesterday. Starting from yesterday, i keep getting the 404 bad request. I simply just wrote a try catch loop for 3 times and it worked through.

However, starting from this morning, my try catch loop could not give me any result. I increased the repeat time to 20 times, and it didn't succeeded once.

To replicate:

python 3.6

import eikon as ek
ek.set_app_id(app_id)
ek.set_timeout(120)
date = '2018-03-28'
symbol_ric = ['AUDCAD=', 'AUDCHF=', 'AUDJPY=', 'AUDNZD=', 'AUD=', 'CADCHF=', 'CADJPY=', 'CHFJPY=', 'EURAUD=',
 'EURCAD=', 'EURCHF=', 'EURGBP=', 'EURJPY=', 'EURNZD=', 'EUR=', 'GBPAUD=', 'GBPCAD=', 'GBPCHF=',
 'GBPJPY=', 'GBPNZD=', 'GBP=', 'NZDCAD=R', 'NZDCHF=R', 'NZDJPY=', 'NZD=', 'CAD=', 'CHF=', 'JPY=']
req, error = ek.get_data(symbol_ric, parameters={'SDate':f'{date}', 'EDate':f'{date}'}, fields=['TR.ASKPRICE','TR.BIDPRICE'], debug=True)

some times the result is timeout, sometimes it is returns a dataframe with some ric missing

full log on one trial with debug=True on is attached.trdebug-log.txt

I tried to get the rate one by one, and it always stuck on AUDCHF=

please advise how to fix this!