# Chunk Upload Asset Canister **URL:** \ **Category:** Developers\ **Tags:** Frontend\ **Created:** [February 24, 2023, 9:26am UTC](https://forum.dfinity.org/t/chunk-upload-asset-canister/18678 "2023-02-24T09:26:59Z")\ **Posts on this page:** 6\ **Page:** 1
**Author:** ![jaesharma](https://sea1.discourse-cdn.com/flex023/user_avatar/forum.dfinity.org/jaesharma/32/7297_2.png) [@jaesharma](https://forum.dfinity.org/u/jaesharma)\ **Post date:** [February 24, 2023, 9:27am UTC](https://forum.dfinity.org/t/chunk-upload-asset-canister/18678/1 "2023-02-24T09:27:00Z")
How to upload big files in asset canister using [@dfinity/assets](https://www.npmjs.com/package/@dfinity/assets) ? with `batch.store()` i was able to upload files upto 1MB but when uploading files of size 5MB i get error: ```auto Code: 400 (Bad Request) Body: Expiry is 36 seconds in the past at HttpAgent.readState (node_modules/@dfinity/agent/lib/cjs/agent/http/index.js:329:19) at processTicksAndRejections (node:internal/process/task_queues:96:5) at async pollForResponse (node_modules/@dfinity/agent/lib/cjs/polling/index.js:48:19) at async caller (node_modules/@dfinity/agent/lib/cjs/actor.js:193:35) at async /custom_asset_canister/node_modules/@dfinity/assets/lib/cjs/index.js:199:38 at async Promise.all (index 1) at async /custom_asset_canister/node_modules/@dfinity/assets/lib/cjs/index.js:193:30 at async Promise.all (index 0) at async AssetManagerBatch.commit (node_modules/@dfinity/assets/lib/cjs/index.js:249:29) at async AssetManager.upload (file:///custom_asset_canister/test/helper.js:83:5) at async Context. (file:///custom_asset_canister/test/unit.test.js:90:1 ``` is it possible to chunk upload big files with @dfinity/assets library? ---
**Author:** ![Vivienne](https://sea1.discourse-cdn.com/flex023/user_avatar/forum.dfinity.org/vivienne/32/29170_2.png) [@Vivienne](https://forum.dfinity.org/u/Vivienne)\ **Post date:** [February 24, 2023, 9:56am UTC](https://forum.dfinity.org/t/chunk-upload-asset-canister/18678/2 "2023-02-24T09:56:16Z")
Looking at the [source](https://github.com/dfinity/agent-js/blob/main/packages/assets/src/index.ts#L299) I would expect it to do chunking automatically. Looking at the asset canister source I don’t see an error message like `Expiry is 36 seconds in the past`, so I think this is an error served by the IC itself. Is there a chance that your system’s time and the IC’s time are drifting apart? ---
**Author:** ![jaesharma](https://sea1.discourse-cdn.com/flex023/user_avatar/forum.dfinity.org/jaesharma/32/7297_2.png) [@jaesharma](https://forum.dfinity.org/u/jaesharma)\ **Post date:** [February 24, 2023, 10:25am UTC](https://forum.dfinity.org/t/chunk-upload-asset-canister/18678/3 "2023-02-24T10:25:55Z")
not sure, might be posssible. i’m running this in containerised docker environment. how could i confirm if this is caused by mis-match time? also if time is mismatch shouldn’t small size files also through same error? rn small files are not having any issue. ---
**Author:** ![Vivienne](https://sea1.discourse-cdn.com/flex023/user_avatar/forum.dfinity.org/vivienne/32/29170_2.png) [@Vivienne](https://forum.dfinity.org/u/Vivienne)\ **Post date:** [February 24, 2023, 1:57pm UTC](https://forum.dfinity.org/t/chunk-upload-asset-canister/18678/4 "2023-02-24T13:57:41Z")
@anon74414410 do you have experience debugging this? ---
**Author:** ![sea-snake](https://sea1.discourse-cdn.com/flex023/user_avatar/forum.dfinity.org/sea-snake/32/7243_2.png) [@sea-snake](https://forum.dfinity.org/u/sea-snake)\ **Post date:** [February 24, 2023, 2:04pm UTC](https://forum.dfinity.org/t/chunk-upload-asset-canister/18678/5 "2023-02-24T14:04:47Z")
The chunked upload (larger files and batch) makes multiple calls to the asset canister in order: - create batch - create chunk (multiple calls in parallel) - commit batch While the non batch upload uses a single call to store files: - store If a file is larger than `maxSingleFileSize`, the library will use the batch implementation under the hood. All 4 canister methods mentioned above are calls and not queries and should have the same time mismatch issues in theory. But it seems I might have made a mistake in the non chunked small file upload error handling, errors from the IC might not throw an exception. I’ll look into this. If I’m correct that means that it seemed the upload of small files succeeded but in reality they did not and aren’t uploaded when you verify it by fetching the files. Regarding time being out of sync in a dev environment, which is something that tends to happen, you can try the `syncTime` method on the agent to make the agent in sync with the replica. ---
**Author:** ![jaesharma](https://sea1.discourse-cdn.com/flex023/user_avatar/forum.dfinity.org/jaesharma/32/7297_2.png) [@jaesharma](https://forum.dfinity.org/u/jaesharma)\ **Post date:** [February 27, 2023, 11:07am UTC](https://forum.dfinity.org/t/chunk-upload-asset-canister/18678/6 "2023-02-27T11:07:04Z")
@sea-snake Tried `syncTime` still getting same error on upload. here is relevant part of my code: ```js this.agent = new HttpAgent({ identity: this.identity, host: AGENT_HOST }); await this.agent.fetchRootKey(); await this.agent.syncTime(); ``` with syncTime this error is thrown: ```auto Caught exception while attempting to sync time: AgentError: Invalid certificate: Signature verification failed ``` & on big file uploads, error remains the same: 400 (Bad Request) Also, small files are getting uploaded successfully, no issue with that. after uploading of 1 MB file, i used `list` from `@dfinity/asset` & got uploaded files listed. **Update :** looks like `Invalid certificate` error is not caused by `syncTime` and i’m not facing it anymore. it seems to be related to this [thread](https://forum.dfinity.org/t/fail-to-verify-certificate-in-development-update-calls/4078/29). but even after `syncTime` the 400 error is still there: ```auto Code: 400 (Bad Request) Body: Expiry is 35 seconds in the past ```