Failed to fetch

E: Failed to fetch File has unexpected size (47871 != 49498). Mirror sync in progress? [IP: 443]
Hashes of expected file:
- Filesize:49498 [weak]
- SHA256:332f3ee4e353b8a5e5a2bdd8fdbd47cf140c73822b82b328815f122e09e195a0
- SHA1:4dc8ef9a3ee3c97b3c26d46e07fdd83997e6880b [weak]
- MD5Sum:bbff3b9c3462257479d72521ee78ec29 [weak]
Release file created at: Wed, 23 Sep 2020 22:09:13 +0000
E: Some index files failed to download. They have been ignored, or old ones used instead.

Same issue, started Friday evening, had to delete our source list rm /etc/apt/sources.list.d/* to get it to work temporarily.

I was able to work around this issue by doing the following in my Dockerfile

FROM nvidia/cuda:10.1-cudnn7-devel-ubuntu18.04
RUN rm /etc/apt/sources.list.d/nvidia-ml.list && apt-get clean && apt-get update