Json & Zip for custom 3D printer electronics

Hi

I "think" i got a zip file made for 1.6.8 and also the JSON needed

https://raw.githubusercontent.com/ThamesValleyReprapUserGroup/Beta-TVRRUG-Mendel90/master/Added-Documents/OMC/package_omc_index.json

I can download and extract the zip with no issue... and its also the download version i got the checksum from

any clue why its keeps on saying CRC mismatch?

To make it clear... this is so i from boards manager can install my board

just checked again this morning that the checksum in the JSON is correct

i do so by first uploading the zip.... then downloading it again and make sure i can extract it. then i get the checksum from it and make sure it's correct in the JSON

for some obscure reason the IDE says

CRC doesn't match. File is corrupted.
java.lang.RuntimeException: java.lang.Exception: CRC doesn't match. File is corrupted.
at cc.arduino.contributions.packages.ui.ContributionManagerUI.lambda$onInstallPressed$20(ContributionManagerUI.java:176)
at java.lang.Thread.run(Thread.java:745)
Caused by: java.lang.Exception: CRC doesn't match. File is corrupted.
at cc.arduino.contributions.DownloadableContributionsDownloader.download(DownloadableContributionsDownloader.java:77)
at cc.arduino.contributions.packages.ContributionInstaller.install(ContributionInstaller.java:103)
at cc.arduino.contributions.packages.ui.ContributionManagerUI.lambda$onInstallPressed$20(ContributionManagerUI.java:173)
... 1 more

i managed to get it half working...

it will show up in board manager and i can click install

BUT...

Version info is not shown in board manger
It's not marked as installed

if i install it will say file is allready there, so it does extract it on the first try

Figured it

in the JSON there was omc in small letters... i changed it to capitals like in the rest of the file and it works