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I got a problem I'm struggling with for quite some time. I have a project (Mixed Reality Toolkit based app targeted for HoloLens) and in the process of migrating the project to suit HoloLens 2, I upgraded the Unity version from 2019.1.f1 to 2019.4.16f1. As it is meant for a HoloLens device, it used Unity's LWRP (Lightweight Render Pipeline). Now I know that since Unity 2019.3 I should actually use the URP (Universal Render Pipeline).

Sadly, after bumping project version and opening it in 2019.4, neither URP nor LWRP seem to work. The Camera preview goes black after entering Play mode, and the Game view shows only the default skybox (pictures below).

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If I don't use any render pipeline, the camera does render (although of course a lot of elements have the default magenta texture, as shaders were coded to use LWRP).

Any ideas what might be the reason? I have correct URP version (2019.4 verified). Or does anyone have some tips on how to debug URP?

Michał Szydłowski
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    Have you upgraded LWRP to use URP according to the following doc [Upgrading from the Lightweight Render Pipeline to the Universal Render Pipeline](https://docs.unity3d.com/Packages/com.unity.render-pipelines.universal@10.2/manual/upgrade-lwrp-to-urp.html)? Besides, the latest release of MRTK is 2.5.3,it resolves the issue of shaders updated for the URP. We recommend that you back up your project first, then upgrade LWRP to use URP, and follow this document to upgrade MRTK to the latest version: https://microsoft.github.io/MixedRealityToolkit-Unity/Documentation/Updating.html – Hernando - MSFT Jan 12 '21 at 08:03
  • @Hernando-MSFT I did follow the doc regarding upgrade to URP, sadly didn't help. And as for MRTK - sure, I plan to upgrade it as well, but the thing is, if I add a new camera (not in mixed reality playspace, but just a regular fresh camera) it still doesn't render anything. So MRTK older version is probably not the reason why it happens. – Michał Szydłowski Jan 23 '21 at 17:50
  • I mean, it could have been the reason if some elements had trouble rendering. But the preview is completely black and no fresh objects I add appear... so it looks like it's still something wrong with render pipeline – Michał Szydłowski Jan 23 '21 at 17:55
  • I tried to reproduce this issue by creating a project from the Lightweight Render Pipeline template and importing the MRTK. And then open this project with Unity2019.4.18 to upgrade. It works fine for me. Could you reproduce this issue on another Unity Project? If it did reproduce, please provide an MVCE(stackoverflow.com/help/minimal-reproducible-example), so that we can locate the issue or find a solution. – Hernando - MSFT Jan 26 '21 at 05:58
  • Okay, I think I narrowed it down. It turns out that it could be an issue with player settings for UWP. If I switch platform to PC, Mac & Linux Standalone, it works fine, cameras are rendering. Only after I switch to UWP, it stops working. Maybe it's something with XR plugin? I'll try and dig into this. – Michał Szydłowski Jan 29 '21 at 13:28

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