JsonCacheInfoRepository: FormatException: Unexpected end of input (at character 1) ^ #450

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1. Migo-17 commented on Oct 3, 2024

   

   Migo-17

   on Oct 3, 2024

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   Any updates on when this issue will be fixed ?
2. aazgersky commented on Nov 22, 2024

   

   aazgersky

   on Nov 22, 2024

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   Faced with same problem on iOS devices
   
3. duocnguyen6799 commented on Feb 21, 2025

   

   duocnguyen6799

   on Feb 21, 2025

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   Is there any update on this? I'm facing the same issue!
4. bothyculture commented on Mar 8, 2025

   

   bothyculture

   on Mar 8, 2025

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   I get this issue a lot too
5. manoj-simform commented on Jun 5, 2025

   

   manoj-simform

   on Jun 5, 2025

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   Do we have any update on this?
6. aazgersky commented on Jun 5, 2025

   

   aazgersky

   on Jun 5, 2025

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   @bothyculture Why you decided to close your PR? We really need this fix
7. hayatshin commented on Oct 9, 2025

   

   hayatshin

   on Oct 9, 2025

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   Same here. any update on this?
8. HeftyCoder commented on Oct 23, 2025

   

   HeftyCoder

   on Oct 23, 2025

   Last edited by HeftyCoder

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   I don't think this is caused when creating the file. Or at least, I haven't gotten the error when creating the .json file. (Note that I am using the JsonCacheInfoRepository.withFile constructor, but I don't think there is a difference).

   I have had this happen when I abruptly closed the app from my IDE and then re-opened it, which somehow caused an existing database file to be emptied completely. I had multiple CacheManagers, but only one at a time active. These were closed and opened when users were logging to different servers.

   I then noticed that despite there being multiple CacheManagers, I had them all with the same cacheKey. Even though only one was active at a time, it seems that this wasn't enough, and probably a race condition was happening where one CacheManager instance corrupted one of the .json files. I made them all have different keys and I have not seen the issue since.

   If you have seen this issue with only one CacheManager, then there is indeed something more serious going on, and I would suggest at least not closing the app abruptly through the IDE. Or you might have forgotten to dispose your CacheManager?
9. alamin-karno commented on Jul 16, 2026

   

   alamin-karno

   on Jul 16, 2026

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   We're hitting this too — flutter_cache_manager 3.4.1, Flutter 3.32.5, Android (observed on a Samsung SM-A325F / Android 13, but not device-specific). FormatException: Unexpected end of input (at character 1) from jsonDecode in JsonCacheInfoRepository._readFile, reported via FlutterError.reportError.

   In our case it's a single CacheManager instance/cache key (not the multi-instance race @HeftyCoder described above), so our best guess is the plain, non-atomic writeAsString in _saveFile() — a process kill mid-write leaves a truncated/empty {databaseName}.json, and every subsequent open() re-decodes the same corrupted file until something else happens to overwrite it.

   Since there's no released fix yet, we worked around it on our end by wrapping JsonCacheInfoRepository to validate the index file before opening, and deleting it if it's not valid JSON, so a corrupted file gets discarded instead of persisting across launches:

   class ResilientJsonCacheInfoRepository extends JsonCacheInfoRepository {
     ResilientJsonCacheInfoRepository({required String databaseName})
         : super(databaseName: databaseName);
   
     @override
     Future<bool> open() async {
       await _deleteFileIfCorrupted();
       return super.open();
     }
   
     Future<void> _deleteFileIfCorrupted() async {
       final directory = await getApplicationSupportDirectory();
       final file = File(join(directory.path, '$databaseName.json'));
       if (!await file.exists()) return;
       try {
         final content = await file.readAsString();
         if (content.trim().isEmpty) {
           throw const FormatException('Cache index file is empty');
         }
         jsonDecode(content);
       } catch (_) {
         await file.delete();
       }
     }
   }

   Posting in case it's useful to others as a stopgap. The real fix is presumably making _saveFile() write atomically (temp file + rename) so a killed process can't leave a truncated file in the first place — happy to help if the closed PR mentioned above needs someone to pick it back up.

   👍React with 👍1Reacted by cljobs