# Certificate issue for sample data download

**URL:** <https://discourse.slicer.org/t/certificate-issue-for-sample-data-download/17454>\
**Category:** Support\
**Created:** [May 4, 2021, 6:28pm UTC](https://discourse.slicer.org/t/certificate-issue-for-sample-data-download/17454 "2021-05-04T18:28:59Z")\
**Posts on this page:** 8\
**Page:** 1

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**Author:** ![muratmaga](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.slicer.org/muratmaga/32/3622_2.png) [@muratmaga](https://discourse.slicer.org/u/muratmaga)\
**Post date:** [May 4, 2021, 6:28pm UTC](https://discourse.slicer.org/t/certificate-issue-for-sample-data-download/17454/1 "2021-05-04T18:28:59Z")

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We have this on going issue with sample data not being available when we run Slicer on our Linux servers at work:

`Switch to module: "SampleData" <b>Requesting download</b> <i>MR-head.nrrd</i> from https://github.com/Slicer/SlicerTestingData/releases/download/SHA256/cc211f0dfd9a05ca3841ce1141b292898b2dd2d3f08286affadf823a7e58df93 ... <font color="red"><b> Download failed: <urlopen error [SSL: CERTIFICATE_VERIFY_FAILED] certificate verify failed (_ssl.c:847)></b></font> `

On the same server (and in the same command line session), I can start firefox and paste the exact url and download the data. There is no http\_proxy or any other variable set. The admin asked this:

“Does slicer have its own certificate store? Or does it have a flag to say which certificate store to use?”

I do not know the answer to this question. Any ideas?

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**Author:** ![jcfr](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.slicer.org/jcfr/32/17825_2.png) [@jcfr](https://discourse.slicer.org/u/jcfr)\
**Post date:** [May 4, 2021, 6:52pm UTC](https://discourse.slicer.org/t/certificate-issue-for-sample-data-download/17454/2 "2021-05-04T18:52:28Z")

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> [@muratmaga](#):
>
> “Does slicer have its own certificate store? Or does it have a flag to say which certificate store to use?”
> 
> I do not know the answer to this question. Any ideas?

We indeed generate own certificate bundle.  
See [Slicer/Base/QTCore/Resources/Certs at main · Slicer/Slicer · GitHub](https://github.com/Slicer/Slicer/tree/master/Base/QTCore/Resources/Certs)

Which version of Slicer is problematic ?

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**Author:** ![muratmaga](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.slicer.org/muratmaga/32/3622_2.png) [@muratmaga](https://discourse.slicer.org/u/muratmaga)\
**Post date:** [May 4, 2021, 7:04pm UTC](https://discourse.slicer.org/t/certificate-issue-for-sample-data-download/17454/3 "2021-05-04T19:04:25Z")

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This was with the latest stable, but as far as I know every version had the issue.

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**Author:** ![jcfr](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.slicer.org/jcfr/32/17825_2.png) [@jcfr](https://discourse.slicer.org/u/jcfr)\
**Post date:** [May 4, 2021, 7:15pm UTC](https://discourse.slicer.org/t/certificate-issue-for-sample-data-download/17454/4 "2021-05-04T19:15:57Z")

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Which operating system ? Is the issue specific to macOS ?

| Slicer version | Operating System | Type of build | SampleData download working |
| --- | --- | --- | --- |
| 4.13.0 / r29885 | Windows | Preview installer | ✅ yes |
| 4.13.0 / r29874 | Linux | Local Developer build | ✅ yes |

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<div class="post-metadata">

**Author:** ![muratmaga](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.slicer.org/muratmaga/32/3622_2.png) [@muratmaga](https://discourse.slicer.org/u/muratmaga)\
**Post date:** [May 4, 2021, 7:42pm UTC](https://discourse.slicer.org/t/certificate-issue-for-sample-data-download/17454/5 "2021-05-04T19:42:17Z")

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This is on Linux. However, the issue is specific to our Linux environment, I think.

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**Author:** ![jcfr](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.slicer.org/jcfr/32/17825_2.png) [@jcfr](https://discourse.slicer.org/u/jcfr)\
**Post date:** [May 4, 2021, 7:49pm UTC](https://discourse.slicer.org/t/certificate-issue-for-sample-data-download/17454/6 "2021-05-04T19:49:30Z")

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> the issue is specific to our Linux environment

It would be great to sort this out.

Few hints:

- Does Slicer pick up a different version of OpenSSL ?
- Is the env. variable `SSL_CERT_FILE` set to a valid bundle ?

> <https://github.com/Slicer/Slicer/blob/0094e9a35bd266cc8b0e677858dabce797c9928f/SuperBuild/python_configure_python_launcher.cmake#L68-L71>

> <https://github.com/Slicer/Slicer/blob/0094e9a35bd266cc8b0e677858dabce797c9928f/SuperBuild/python_configure_python_launcher.cmake#L114-L118>

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<div class="post-metadata">

**Author:** ![muratmaga](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.slicer.org/muratmaga/32/3622_2.png) [@muratmaga](https://discourse.slicer.org/u/muratmaga)\
**Post date:** [May 4, 2021, 9:38pm UTC](https://discourse.slicer.org/t/certificate-issue-for-sample-data-download/17454/7 "2021-05-04T21:38:00Z")

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> [@jcfr](#):
>
> Does Slicer pick up a different version of OpenSSL ?

This is what I get from the command prompt prior to launching Slicer:

```
    amaga@pplhpc1ood01:/gpfs/home/amaga/Desktop$ ldconfig -p |grep -i ssl
    	libssl3.so (libc6,x86-64) => /lib64/libssl3.so
    	libssl.so.10 (libc6,x86-64) => /lib64/libssl.so.10
    	libssl.so (libc6,x86-64) => /lib64/libssl.so
    	libevent_openssl-2.0.so.5 (libc6,x86-64) => /lib64/libevent_openssl-2.0.so.5

```

setting

`export SSL_CERT_FILE=/etc/pki/ca-trust/extracted/pem/tls-ca-bundle.pem`

has no effect.

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<div class="post-metadata">

**Author:** ![muratmaga](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.slicer.org/muratmaga/32/3622_2.png) [@muratmaga](https://discourse.slicer.org/u/muratmaga)\
**Post date:** [May 5, 2021, 6:37pm UTC](https://discourse.slicer.org/t/certificate-issue-for-sample-data-download/17454/8 "2021-05-05T18:37:06Z")

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Nor setting the SSL\_CERT\_FILE variable to the Slicer.crt in Slicer install directory.