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Fixed in 2021.3.34f1, 2022.3.16f1, 2023.2.5f1, 2023.3.0a19, 7000.0.0a1



Found in






Issue ID




Unity fails to load an audio file via web request when the path of the audio file has a "+" in it



The original bug report is by design.

The complain about missing docs is valid. Rescoping the case to add missing method signatures to API docs.



How to reproduce:
1. Open the attached ““ project
2. Open the “SampleScene“ Scene
3. Enter Play Mode

Expected result: Audio file plays and “Audio file loaded! You should hear it playing.“ text is visible in the Game view
Actual result: Audio file doesn’t play and “Error: HTTP/1.1 404 Not Found“ text is visible in the Game view

Reproducible with: 2021.3.32f1, 2022.3.14f1, 2023.2.2f1, 2023.3.0a16

Reproducible on: macOS 14.0 Sonoma (Intel)
Not reproducible on: No other environment tested

- Also reproducible in Player
- The issue is only reproducible with audio files
- The user noted that File.Exists returns “true”
- The user noted that they use the C# built URI class to build a valid local URI and that this helper escapes special reserved characters (for example, converts “Space” into “%20”), but considers the “+” valid
- The user noted that according to the spec on URL encoding RFC 3986, a generic URI uses a subset of reserved characters where the “{+}” is not considered reserved and that the C# implementation confirms this. The “{+}” is generally only interpreted as a “Space” when crafting an “application/x-www-form-urlencoded” type String
- The user noted that they tried testing if Unity was replacing the “+” with “Space”, but weren’t able to make it work
- The user noted that although Unity provides its own method to escape a URL via UnityWebRequest.EscapeURL, they have not found any way to use this to create a valid URI that is accepted by the multimedia request
- The user noted that using EscapeURL on the path before entering it into the URI helper will cause a UriFormatException
- The user noted that using EscapeURL on the output of Uri.absoluteUri will cause Unity to return an “Unable to connect” error
- The user noted that when using "file:///" + UnityWebRequest.EscapeURL(path), the audio file is found, and this works on Windows, but fails on MacOS
- The user noted if the URI of the failed audio file load is copied and pasted into any browser, it will find and play the file

  1. Resolution Note (fix version 2023.3.0a19):

    Documentation issue - some signatures were missing in API docs.

Comments (1)

  1. Doddler

    Nov 30, 2023 01:32

    I disagree with this resolution, using a Uri cannot be the recommended method because the unity documentation does not acknowledge that such a method even exists, and the sample code provided by unity also does not use a Uri. Any user attempting to use UnityWebRequestMultimedia based on the documentation will encounter this bug.

    Additionally, the + character is valid in a Uri in Chrome, Firefox, Safari, Edge, and even C#'s own Uri class, so I disagree that it should even be unescaped like it is. It would be fine if the Uri version of the method was recommended, but there's no way to even know it exists.

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