To Whom It May Concern:

On 8/27 when I tried to log in to MTGA I got this error message:

The procedure entry point SetThreadDescription could not be located in the dynamic link library C:\Program Files\Wizards of the Coast\MTGUnityPlayer.dll

When I looked up how to fix this issue it said that SetThreadDescription is generally available in Windows 10 version 21H1 and later. It would seem as though Windows 10 is now the minimum requirement from my research. So, if you are getting a lot of complaints maybe this is the issue. I hope you can fix this or I just wasted a month or 2 for nothing as I have no way to get a new computer as I got this from a family member. You can find all the information I could get for you that the request line said you may need from them as I do not want my information on an open chat. I hope it helps. I could not find the information from the game since it will not open. Thank you for your time and consideration. Take care, be safe and have better days.

Unity 6 のシステム要件
Windows Windows 10 バージョン 21H1 (ビルド 19043) 以降
これに引っかかったんだと思う。

たぶんこれ。

Unity - マニュアル: Unity 6 のシステム要件
https://docs.unity3d.com/jp/current/Manual/system-requirements.html
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私も起きたが、最小要件を疑っている。
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最小要件が変わっただろう
スタートガイドに関するFAQ
では、

最小要件:

プロセッサ: AMD Athlon 64 X2デュアルコア5600+または同等のプロセッサ
グラフィックカード: GeForce GTX 8800または同等のグラフィックカード
RAM: 2GB
オペレーティングシステム: Windows 7

とまだなっているが、

Game Update - Unity Update and Upgrade
と、2026/8/25 のアップデートで
インストールエラーが起こったあとのUnity のバージョンを見てみると
6000.3.14.35903
となっており、

おそらく最小要件がWindows7 ではなくなっただろう。
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Aug 25, 2026
Game Update - Unity Update and Upgrade
Completed - The scheduled maintenance has been completed.
Aug 25, 18:30 UTC
In progress - Scheduled maintenance is currently in progress. We will provide updates as necessary.
Aug 25, 15:30 UTC
Scheduled - @MTG_Arena maintenance will occur to deploy a full client update.

📥 Full download required.
🔄 Restart required. No downtime for those who update.
⏲️ ~3 hour estimated deployment.
📝 Patch notes soon after.
Aug 21, 18:41 UTC
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https://magicthegatheringarena.statuspage.io/
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スタートガイドに関するFAQ – MTG Arena
https://mtgarena-support.wizards.com/hc/ja/articles/360029669912-%E3%82%B9%E3%82%BF%E3%83%BC%E3%83%88%E3%82%AC%E3%82%A4%E3%83%89%E3%81%AB%E9%96%A2%E3%81%99%E3%82%8BFAQ
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Unity - マニュアル: Unity 6 のシステム要件
https://docs.unity3d.com/jp/current/Manual/system-requirements.html