There are a number of missing texture assets which are failing to be read when the editor opens. This is causing a warning to be thrown each time the editor opens, potentially causing CI/CD tests (including Horde) to fail.
The current work around to these warnings is to either disable the LogStreaming messages, or to add replacement files to these locations.
1. Open an empty project in UE 5.5.2.
2. Observe following warnings in Output Log.
"LogStreaming: Warning: Failed to read file '../../../Engine/Plugins/Developer/PlasticSourceControl/Resources/Icon128.png' error.
LogStreaming: Warning: Failed to read file '../../../Engine/Platforms/VisionOS/Content/Editor/Slate/Launcher/Platform_VisionOS_24x.png' error.
LogStreaming: Warning: Failed to read file '../../../Engine/Platforms/VisionOS/Content/Editor/Slate/Launcher/Platform_VisionOS_128x.png' error.
LogStreaming: Warning: Failed to read file '../../../Engine/Plugins/Interchange/Editor/Content/Old/Tiles/Outer/alertSolid.png' error.
LogStreaming: Warning: Failed to read file '../../../Engine/Plugins/Developer/PlasticSourceControl/Resources/Icon128.png' error.
LogStreaming: Warning: Failed to read file '../../../Engine/Platforms/VisionOS/Content/Editor/Slate/Launcher/Platform_VisionOS_24x.png' error.
LogStreaming: Warning: Failed to read file '../../../Engine/Platforms/VisionOS/Content/Editor/Slate/Launcher/Platform_VisionOS_128x.png' error.
LogStreaming: Warning: Failed to read file '../../../Engine/Plugins/Interchange/Editor/Content/Old/Tiles/Outer/alertSolid.png' error.
LogStreaming: Warning: Failed to read file 'Common/Selector.png' error."
There's no existing public thread on this issue, so head over to Questions & Answers just mention UE-237138 in the post.