EFS - files not found sometimes and randomly

Question

Hi, 
We use EFS to read and write files from Lamdas (call in a step function).
The first lambda read a file from S3 and write it in EFS.
A second lambda read to this file from EFS.

The problem is that sometimes (rarely but enough to be a problem) the second lambda don't find the file on EFS (Error NotFoundFile). We check the file is here on the first lambda so it's not a problem of writing just the second lambda seems not to have access to it yet. There is some miliseconds between the 2 calls.

All quotas of EFS seems to be ok and the error is not reproducible but occurs several times per day.
Have you an idea to resolve the problem ?

Answer

We finally found the problem, it seems that event notifications from S3 are sometimes duplicated. 
I don't precise in my first message, but a third lambda delete file when it's not usefull anymore. So when event is duplicated, it is treated once well and it is deleted during the second treatment, that causes errors. Hope it can be helpful for someone else :)

EFS - files not found sometimes and randomly

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