# Windows blocks RhinoCycles.rhp – “ID already in use” error

**URL:** <https://discourse.mcneel.com/t/windows-blocks-rhinocycles-rhp-id-already-in-use-error/223959>\
**Category:** Rhino for Windows\
**Tags:** windows\
**Created:** [October 27, 2026, 3:42pm UTC](https://discourse.mcneel.com/t/windows-blocks-rhinocycles-rhp-id-already-in-use-error/223959 "2026-10-27T15:42:54Z")\
**Posts on this page:** 1\
**Page:** 1

<div class="post-metadata">

**Author:** ![Tomáš\_Němeček](https://avatars.discourse-cdn.com/v4/letter/t/c5a1d2/32.png) [@Tomáš\_Němeček](https://discourse.mcneel.com/u/Tom%C3%A1%C5%A1_N%C4%9Bme%C4%8Dek)\
**Post date:** [October 27, 2026, 3:42pm UTC](https://discourse.mcneel.com/t/windows-blocks-rhinocycles-rhp-id-already-in-use-error/223959/1 "2026-10-27T15:42:54Z")

</div>

Hi,

Since recently, Rhino 8 shows this error at startup:

> Unable to load RhinoCycles.rhp plug-in: ID already in use.

The root cause seems to be **Windows Smart App Control** blocking `RhinoCycles.rhp`. Rhino itself is installed from the official McNeel download.

Note: my Windows is in Czech, so some screenshots are in Czech. Translations are below.

**Screenshot 1 – Windows Security notification**  
Translation: _“Part of this app has been blocked. Some features of Rhino 8 may not work because we can’t confirm who published RhinoCycles.rhp that the app is trying to load.”_

 ![image](https://global.discourse-cdn.com/mcneel/uploads/default/original/4X/1/2/b/12b3c6cac04b2204b5a4f08bfb82e0382a4c0fe2.png)

**Screenshot 2 – Rhino plug-in error** (shown right after the block, probably just a consequence of it)

 ![image](https://global.discourse-cdn.com/mcneel/uploads/default/original/4X/3/f/d/3fdea338b41ae787c819f272406231a90398722c.png)

**Screenshot 3 – Digital signature of RhinoCycles.rhp**  
The file is signed by _McNeel Software Development_, issued by **“Trusted Rhino Plug-ins”** , signed on 11 Aug 2026 with an [SSL.com](http://SSL.com) timestamp. Windows reports _“The certificate in the signature cannot be verified”_ and _“Windows does not have enough information to verify this certificate.”_ As far as I understand, the certificate chains to McNeel’s internal CA, which isn’t a trusted root in Windows. Smart App Control therefore treats the file as unsigned.

 ![image](https://global.discourse-cdn.com/mcneel/uploads/default/original/4X/5/b/1/5b16771dc4bbad57b368f46633ad5a98cae94cbb.png)

**Screenshot 4 – Event Viewer, CodeIntegrity/Operational, Event ID 3077**

> Code Integrity determined that a process (\Program Files\Rhino 8\System\Rhino.exe) attempted to load \Program Files\Rhino 8\Plug-ins\RhinoCycles.rhp that did not meet the Enterprise signing level requirements or violated code integrity policy (Policy ID:{0283ac0f-fff1-49ae-ada1-8a933130cad6}).

 ![image](https://global.discourse-cdn.com/mcneel/uploads/default/original/4X/a/6/f/a6f48479663297b1706b7ae47e9c29785aa9cfca.jpeg)

The log also shows repeated 3033 / 3089 events every time Rhino starts.

**System:**

- Version 8 SR34  
(8.34.26223.11001, 2026-08-11)  
Commercial
- Windows 11 Pro (Czech), Smart App Control **On**

FYI I saw .. topic [Why Smart App Control has blocked part of this rhino8 app](https://discourse.mcneel.com/t/why-smart-app-control-has-blocked-part-of-this-rhino8-app/220158) it looks it is the same issue.

Pls. Help 🙂  
Thank you.  
Tomas.