Why is OmicsoftUpdater failing on Linux with "SendFailure (Error writing headers)"?

Starting in 10/16/2020, OmicSoftUpdater retrieves the latest updates from https://resources.omicsoft.com, using HTTPS communications. In Linux systems, the mono package does not have any certificates accepted by default, so all HTTPS connections will be rejected (no trusted SSL certificates).

So if you see an error like this, it is probably because the certificate wasn't accepted:

[omicsoft@test-08 oshell]$ mono OmicsoftUpdater.exe
Fetching update information (PROD)...
[4:37 PM] Downloading from https://resources.omicsoft.com/software_update/oshell/Manifest.txt...
[4:37 PM] Failed to download file: /tmp/tmp3c97f2f8.tmp. Error=Error: SendFailure (Error writing headers). StackTrace=  at System.Net.HttpWebRequest.EndGetResponse (IAsyncResult  asyncResult) [0x00000] in <filename unknown>:0

Okay, how do I fix it?

Retrieve the HTTPS certficate from https://resources.omicsoft.com and add it to your machine's "trusted store". The mono package includes a certmgr command that can do this.

Run this command under the same user that launches OmicSoft Server/oshell to add the certificate to the user's trusted certificate store:

certmgr --ssl https://resources.omicsoft.com

Alternatively, add the certificate to your machine's certificate store:

certmgr --ssl -m https://resources.omicsoft.com

Type 'y' a few times to accept each certificate, then try OmicsoftUpdater again.

Expected output

[omicsoft@test-08 oshell]$ certmgr --ssl https://resources.omicsoft.com
Mono Certificate Manager - version 4.0.4.0

Manage X.509 certificates and CRL from stores.
Copyright 2002, 2003 Motus Technologies. Copyright 2004-2008 Novell. BSD licensed.


Self-signed X.509 Certificate v3
  Issued from: C=GB, S=Greater Manchester, L=Salford, O=Comodo CA Limited, CN=AAA Certificate Services
  Issued to:   C=GB, S=Greater Manchester, L=Salford, O=Comodo CA Limited, CN=AAA Certificate Services
  Valid from:  1/1/2004 12:00:00 AM
  Valid until: 12/31/2028 11:59:59 PM 
Import this certificate into the Trust store ?y

X.509 Certificate v3
  Issued from: C=US, S=New Jersey, L=Jersey City, O=The USERTRUST Network, CN=USERTrust RSA Certification Authority
  Issued to:   C=GB, S=Greater Manchester, L=Salford, O=Sectigo Limited, CN=Sectigo RSA Domain Validation Secure Server CA
  Valid from:  11/2/2018 12:00:00 AM
  Valid until: 12/31/2030 11:59:59 PM
Import this certificate into the CA store ?y

X.509 Certificate v3
  Issued from: C=GB, S=Greater Manchester, L=Salford, O=Comodo CA Limited, CN=AAA Certificate Services
  Issued to:   C=US, S=New Jersey, L=Jersey City, O=The USERTRUST Network, CN=USERTrust RSA Certification Authority
  Valid from:  3/12/2019 12:00:00 AM
  Valid until: 12/31/2028 11:59:59 PM
  *** WARNING: Certificate signature is INVALID ***
Import this certificate into the CA store ?y

X.509 Certificate v3
  Issued from: C=GB, S=Greater Manchester, L=Salford, O=Sectigo Limited, CN=Sectigo RSA Domain Validation Secure Server CA
  Issued to:   CN=*.omicsoft.com
  Valid from:  7/14/2020 12:00:00 AM
  Valid until: 7/14/2022 11:59:59 PM
Import this certificate into the AddressBook store ?y

4 certificates added to the stores.