Try updating studio if you can, If you can’t, try these methods [May not work]:
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Try mod manager on different channels (Mod manager is in github and forum, Roblox Studio Mod Manager)
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Try launching studio from the start menu, should update it.
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Visit that url, a black screen with text should appear, read what it says and reply back. if it downloads something and closes, that means it worked and you need to launch it.
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Final method, uninstall and re-install studio. Or just contact support.