MLA-C01 Practice Question: Refer to the exhibit

Exhibit

{
    "TrainingJobName": "my-training-job",
    "TrainingJobStatus": "Failed",
    "FailureReason": "ClientError: Cannot evaluate expression: loss",
    "AlgorithmSpecification": {
        "TrainingImage": "123456789012.dkr.ecr.us-east-1.amazonaws.com/custom-latest",
        "TrainingInputMode": "File"
    },
    "ResourceConfig": {
        "InstanceType": "ml.m5.large",
        "InstanceCount": 1,
        "VolumeSizeInGB": 30
    },
    "StoppingCondition": {
        "MaxRuntimeInSeconds": 86400
    },
    "OutputDataConfig": {
        "S3OutputPath": "s3://my-bucket/output"
    }
}

Refer to the exhibit. A data scientist ran a training job using a custom algorithm container. The job failed with the error shown. What is the most likely cause?

Answer choices

Why each option matters

Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.

Correct answer & explanation

✓

The algorithm script references an undefined variable or metric named 'loss'

The error 'Cannot evaluate expression: loss' indicates that the training script attempted to compute or log a variable named 'loss' that is not defined in the code. The training image access, S3 output path, and instance type are not related to this specific error.

Answer analysis

Option-by-option breakdown

For each option: why learners choose it and why it is or isn't the right answer here.

✗
The S3 output path is incorrect
Why it's wrong here
An incorrect S3 path would cause a different error, such as 'NoSuchBucket'.
✓
The algorithm script references an undefined variable or metric named 'loss'
Why this is correct
The error directly states it cannot evaluate 'loss', meaning the variable is not defined or out of scope.
✗
The training image is not accessible
Why it's wrong here
An inaccessible image would cause an error like 'Cannot pull image' or 'AccessDenied', not a ClientError about 'loss'.
✗
The instance type is insufficient
Why it's wrong here
Insufficient instance type would likely cause an out-of-memory error, not a client error about an expression.

Quick reference

AWS S3 Storage Class Comparison

Storage Class	Min Duration	Retrieval	Use Case
S3 Standard	None	Immediate	Frequently accessed data
S3 Standard-IA	30 days	Immediate	Infrequent access, rapid retrieval
S3 One Zone-IA	30 days	Immediate	Non-critical infrequent data
S3 Intelligent-Tiering	None	Immediate–hours	Unknown or changing access patterns
S3 Glacier Instant	90 days	Milliseconds	Archive with instant retrieval
S3 Glacier Flexible	90 days	Minutes–hours	Archive, flexible retrieval
S3 Glacier Deep Archive	180 days	Hours	Long-term compliance archive

Go deeper

MLA-C01 Practice Question: Refer to the exhibit

Exhibit

Why each option matters

Option-by-option breakdown

AWS S3 Storage Class Comparison

Related to this question