The error message STORAGE_LIMIT_EXCEEDED occurs if Data and File Storage Allocations have been exceeded. See Monitor Data and Storage Resources to review your current usage.
Note: Data storage amount limit exceeded is not strictly enforced in production environments to help ensure that business-critical data may continue to be created despite exceeding contractual limits.
If receiving storage limit exceeded messages in production, contact your Account team immediately to discuss available options. Support does not have the ability to increase storage limits in production and it may only be increased through provisioning processes initiated via a Sales Order.
Going over either 'Data Storage' or 'File Storage' allocations will cause the error to be displayed when creating records or uploading files in a sandbox.
For example, if Data Storage is only at 50%, but File Storage is at 110%, then the error will be displayed for both saving or creating records and/or uploading files.
It's not possible to allocate available Data Storage for File Storage or vice versa. Both limits will need to be maintained under 100%.
See also
Sandbox Licenses and Storage by Type
Monitor Data and Storage Resources
1) Delete unnecessary or extra data in your full-copy sandbox to comply with contractual limits.
2) Contact your Account Team to begin the process to provision a storage level increase in production and then match the new limits over to your full sandbox.
Note: Increases to sandbox storage levels beyond what's currently provisioned in production for full sandboxes or what's allocated via a sandbox license type is against Salesforce policy, contractual limits, and not possible under normal circumstances.
1) Use the license match tool available in the sandbox via Setup, enter Company Information in the Quick Find box, select Company Information, and then click Match Production Licenses.
Note: During the sandbox preview window, the Match Production Licenses tool may not be available when the sandbox's release version does not match production. If the tool is unavailable, please log a case with Salesforce Support to request manually matching available storage.
2) Refresh the sandbox to bring over the new limits from production.
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