Context: Custom Gem with JSON Knowledge Base
Description: Since approximately Dec 16/17, the model is failing to retrieve or index data from valid JSON files past a specific timestamp (Dec 1st, 2025). The file is valid (approx 150KB), but the model exhibits a “hard cutoff” behavior, ignoring all recent entries despite repeated re-uploads and cache clearing.
Symptoms:
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RAG fails to read the tail end of JSON structures.
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Deleting and recreating the Gem does not resolve the issue.
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The model hallucinates that data does not exist, confirming a retrieval failure in the backend parser.
Suspected Cause: Recent backend updates regarding “Context Caching” or JSON parsing depth limits are silently truncating input files. This renders the “Custom Gem” feature unusable for logging workflows.
Request: Investigate the indexing pipeline for JSON/structured files immediately. The current retrieval degradation is unacceptable.
Hi @Rodolfo_Berardini, welcome to the community!
Apologies for the delayed response.
Custom Gems primarily uses Gemini 3. If you are on a Free account, Pro access is limited to a small number of prompts per day, after which the model may degrade or fail to retrieve complex knowledge.
If deleting Gems didn’t work, try deep resetting by uploading JSON with a completely new file name.
Please follow Caching Instructions for designing caching and also check Rate limits.
Thank you!
….DO YO REALLY THINK CAN I WRITE THIS CASE as free USER???
Hi,
Thank you for your response, but unfortunately it doesn’t address the specific technical problem I reported.
Let me clarify what the actual issue is:
The Problem (Restated)
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My Custom Gem uses a valid JSON file (~150KB) as knowledge base
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Since approximately Dec 16/17, the RAG system exhibits a “hard cutoff” behavior
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All JSON entries after December 1st, 2025 are completely invisible to the model
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Earlier entries (before Dec 1st) are retrieved correctly
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The file structure is valid - this is NOT a formatting issue
What I Already Tried (None of This Worked)
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Deleting and recreating the Gem: NO EFFECT
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Uploading with different filenames: NO EFFECT
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Re-uploading the same file multiple times: NO EFFECT
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The model consistently hallucinates that recent data “doesn’t exist”
Why Your Response Doesn’t Apply
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“Custom Gems primarily uses Gemini 3” - Irrelevant to the retrieval issue
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Rate limits / Pro account quotas - This is NOT a rate limit problem; it’s a data retrieval failure in the RAG indexing pipeline
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“Try uploading JSON with completely new file name” - Already tested, no effect
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Caching instructions - The problem is NOT caching; the backend parser is truncating or ignoring data past a timestamp threshold
This Is a Backend Regression, Not User Error The same JSON file worked perfectly until mid-December. Then, suddenly, all entries after Dec 1st became invisible. This indicates:
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A change in how the RAG system indexes/parses JSON files
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Possibly related to recent “Context Caching” updates
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Or a hidden depth/size limit that was recently introduced
What I Need
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Escalation to the technical team responsible for the Custom Gems RAG indexing pipeline
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Confirmation of whether backend changes were deployed around Dec 16/17 that affect JSON parsing
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Technical documentation on any new limits/constraints for structured files in Custom Gems
The suggestions about rate limits and caching don’t address the core issue: the RAG system stopped reading the tail end of my JSON structure.
Can someone from the engineering team who works on the Gems retrieval architecture please review this case?
Thank you.
I face the same probelm as you .I’m just a causal user,My Custom Gem is for entertaining purpose but the same problem as you did occured too…I feel your pain,hope you got a solution soon…After Google update to Gemini 3….My Custom Gem is ruined too..I don’t know why they didn’t prioritize this because…well if this function broke..it lost its main feature and can’t perform what it design to be right?