Failed to fetch error while installing pi-hole

[Mylearning_Learn]

Failed to fetch http://mirror.ossplanet.net/raspbian/raspbian/pool/main/l/lighttpd/lighttpd_1.4.53-4+deb10u1_armhf.deb Hash Sum mismatch
Hashes of expected file:
- SHA256:9ca2d3c4707eb342115d0404939ee62d2021f983817f8be8b1525554c3208a31
- SHA1:75cf0688d436093d04612ba818ed49710f14d905 [weak]
- MD5Sum:626c6e0e4398623ed9ece7620601027a [weak]
- Filesize:292832 [weak]
Hashes of received file:
- SHA256:d1b75631e765cdfb6758d3f26545dd30584cc8f20cf2d16426cf4c36b0259dcb
- SHA1:5cefc12bbded84271cd14f60c033ce9a7c92b62b [weak]
- MD5Sum:51462d03567cf8ee0da707ff74b90faf [weak]
- Filesize:292832 [weak]
Last modification reported: Sat, 26 Sep 2020 16:08:12 +0000
E: Failed to fetch http://mirror.ossplanet.net/raspbian/raspbian/pool/main/s/sqlite3/sqlite3_3.27.2-3+deb10u1_armhf.deb Hash Sum mismatch
Hashes of expected file:
- SHA256:c9dde056adcf68ed14c126e71efd40676bd045a153953a359a4751a09efd199f
- SHA1:bd1829f760018f096b3104d239252ffaf3ccd5ec [weak]
- MD5Sum:ec41c9660a12c05b2efba2e9676da7a7 [weak]
- Filesize:838984 [weak]
Hashes of received file:
- SHA256:29356092cf27ad99343bf3908e192c4fe0fcd090589861a02efe8039019db5fe
- SHA1:e3782e5d7c822209bffc761295df28286889dd0a [weak]
- MD5Sum:665fed00d95fe79ac8d415f5de8e24e1 [weak]
- Filesize:838984 [weak]
Last modification reported: Sat, 05 Dec 2020 22:08:32 +0000
E: Unable to fetch some archives, maybe run apt-get update or try with --fix-missing?

I am trying to install it on raspberry Pi 3b

[Mylearning_Learn]

This has been fixed by following the solution given in another thread.
Changed the name server in cat /etc/resolv.conf
added namesever 8.8.8.8 to this and then re run the installation and it worked.

[DanSchaper]

That may just be serendipitous. The error of Hash Sum mismatch means the information downloaded from that mirror (ossplanet.net) did not match what the package said it should. Just running apt again would have fixed it.