Unable to Upload File More Than 12 MB in Salesforce Apex? Causes & Fixes

When i upload file more than 12 MB file upload is failing while using Apex it’s not a bug in your code it’s due to Salesforce platform limits.

Apex has strict governor limits on how much data it can consume in a single transaction. When a file exceeds that limit, the upload will be rejected.

When you upload a file with Apex, the file contents is first loaded into memory.

Salesforce allows:

If the file size is big (especially after encoding), it will quickly exceed this limit. At that point Salesforce halts the process and the upload fails.

This problem usually shows up when:

The processing memory usage is higher, and your file can be bigger than 12MB (but not much bigger).

So:

Apex is not built for large file uploads directly. When the file is large, do not upload it via Apex at all.

If you’re working on UI:

It is the easiest and most foolproof way.

Rather than submitting the entire file at once:

If you’re working with integrations:

For very large files:

This issue is not about incorrect code, it’s about how Apex handles memory.

Salesforce simply doesn’t allow large files to be processed fully inside Apex. The right solution is to change the approach, either avoid Apex for uploads or handle files in smaller parts.