My iphone x wont update. it says error occured but the network is strong

Could you check your iPhone storage, since iPhones may get a pop-up like that if the storage is full.

How to check the storage on your iPhone and iPadAppleOfficial Apple Support › en-us

After you have cleared some space (ex. by deleting some photos or files) try updating again. If you have further issues feel free to contact me from Apple support!

Sincerely, Ryan

Gosiame ~ Does your iPhone X still have its original battery?

And what's the Maximum Capacity % here?...

Settings > Battery > Battery Health

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77% is not healthy and is probably the reason you can't update. Apple recommends replacing the battery at <80%. So have the weak, aging battery replaced and all will be well:

iPhone Battery & Power Repair

About genuine iPhone batteries

Repair Provider Verification

(Articles found by searching Apple's Knowledge Base.)

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