JSON could not be serialized because of error: The data couldn't be read because it isn't in the correct format.

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Level 1

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JSON could not be serialized because of error: The data couldn't be read because it isn't in the correct format.

Hello,

Please can anyone shed any light on this error message:

"JSON could not be serialized because of error: The data couldn't be read because it isn't in the correct format."

I've been using this App (IMSLP) without any problems for years and years on my ipad Pro (which is up to date)and now I can't download any further data - the problem exists also on my iPhone 13.

Any help is appreciated.

Thanks

Mike

iPad (10th generation)

Posted on Nov 12, 2025 11:25 PM

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Answer 1

Rudegar

Level 10

180,186 points

Nov 12, 2025 11:38 PM in response to miketwisse

json is short for JavaScript Object Notation

which is often used for app configuration

your app IMSLP have an corrupted configuration file, then if it was me then I would try to delete the app and

reinstall it from app store

if that was not enough then I would reach out to the developer of the app about options

maybe from

IMSLP:Apps - IMSLP

otherwise How to contact an app developer - Apple Support

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