Storage Upload Failures – mxHero Help Center

Use this page when a rule could not save an email or its attachments to cloud storage, when recipients cannot open the links mxHERO created, or when a storage account needs re-authorization. It covers Box, OneDrive and SharePoint, Google Drive, Egnyte, Dropbox and mxHERO Shares.

Check these first

Check the account status. Open Settings › Integrations › Accounts. An account marked not synced or needing revalidation must be re-authorized. See Re-authorizing Storage Accounts.
Check the organization connection. For Box, Google Drive and OneDrive organization connections, open Settings › Integrations › Applications and click Verify (Box, Google Drive) or check the install status (OneDrive).
Filter Email Flow Logs by storage errors. In Reports › Email Flow Logs, set Delivery status to With storage errors and pick an error code. Open a message to see the storage_executed events and the provider's error code.
Look in Reports › Notifications for storage_credential_no_access or storage_error.
Check the provider's status page if many accounts fail at once.

What happens when an upload fails

mxHERO retries temporary errors automatically (provider rate limits, timeouts, server errors), for up to 45 minutes for Protect Attachments, Secure Email and Zip Attachments, and longer for copy and archiving rules. What happens after that depends on the rule:

Rule	On a final storage error
Protect Attachments, Secure Email, Zip Attachments (default)	The original message is delivered with its attachments.
Same, with When the email could not be processed set to Bounce email to sender in More actions...	The message is not delivered. The sender gets a `[BOUNCED] <subject>` notice from `noreply@mxhero.com`.
Copy Emails (Email Flow)	The original was already delivered. Optionally, the message is forwarded to an address you set in More actions.
Mailbox rules	The message is retried on the next run and counted as an error in the rule's account list.

Note: If retries run out (as opposed to a final error), the original message is delivered even when the rule is set to reject.

Authorization and account errors

Symptom or code	Cause	Fix
Notification `storage_credential_no_access`; account shows not synced	A user's storage token stopped working (password change, revoked app, expired refresh token). The account owner gets an email "Your mxHero requires authentication" at most once a day for 7 days.	Re-authorize the account: use the link in the email (valid 7 days), or click Authorize on the account in Settings › Integrations › Accounts.
`FORBIDDEN_STORAGE_ACCOUNT` when you verify Box	mxHERO's Box app is not authorized in your Box Admin Console.	In the Box Admin Console, authorize the mxHERO app under Platform › Platform Apps (Client ID `3qjybyfh5w6ah97qn1oddmmjtcjxit6t`), then click Verify again. See Connecting Box.
`INVALID_ENTERPRISE_ID` / `organization_or_enterprise_id_not_found` (Box)	The Box enterprise connection is missing or wrong.	Remove and reinstall Box sync in Settings › Integrations › Applications.
`user_not_found` (Box)	The sender or recipient has no Box user with that login in your enterprise.	Create the Box user, map a storage account to the mxHERO account, or use a fixed (manual) storage account in the rule.
`no_storage_account`	The rule uses automatic account selection, and no storage account could be found for the sender or recipient.	Map storage accounts in Settings › Accounts and Groups, or choose a manual account in the rule.
`access_token`, `organization_or_tenant_not_found` (OneDrive for organizations)	The tenant consent was revoked or the app can no longer get a token. All organization users get an email "mxHero requires authentication to …".	Click Re-install on OneDrive sync in Settings › Integrations › Applications and grant consent as a Global Administrator.
`APP_IS_NOT_INSTALLED`, `USER_MUST_BE_ADMIN` (Google Drive for organizations)	The Google Workspace Marketplace app is not installed domain-wide, or the verify email is not an admin.	Install the mxHERO Mail2Cloud app domain-wide from the Marketplace, then verify with a Google Workspace admin email.
`invalid_user`, `Domain … not in organization` (Google Drive)	The user's email domain is not a domain or alias of your mxHERO organization.	Add the domain as an alias in Settings › Organization and domains.
`user … not found` (Dropbox)	The user is not a member of the connected Dropbox team.	Add the user to the team, or pick another account. Dropbox requires a Business or Teams account.
`TENANT_REQUIRED` (Egnyte Gov)	The Egnyte Gov tenant host is missing.	Re-authorize the account and enter the tenant host, for example `example.egnytegov.com`.

Important: Mail2Cloud does not email anyone when a Box or Google Drive organization connection loses access. Check Settings › Integrations › Applications if uploads for all users stop at once.

Upload and folder errors

Symptom or code	Cause	Fix
`storage_error_storing_file`, `box_api_exception`, `onedrive_<code>`	The provider rejected the upload. The provider's message and request ID are in the event details.	Read the provider message. Common causes: quota exceeded, no write permission on the target folder, file type or size blocked by provider policy.
`no_folder_found` (not retried)	The rule points to a folder that no longer exists or that the account cannot see.	Fix the path in the rule, or give the account access to the folder.
`add_location_blank_folder` (warning)	A path variable resolved to an empty value, so the folder was named `EMPTY`.	Check the variables in the storage file path. See Storage File Paths.
File or folder names look shortened or have missing characters	mxHERO cleans names: each folder and file name is cut to 200 characters, and characters that providers reject are removed.	Expected behavior. See File and Folder Naming Rules.
OneDrive or SharePoint errors on deep folder structures	OneDrive and SharePoint limit total path length. mxHERO does not shorten the full path.	Use shorter folder patterns.
`upload_conflict`, `upload_conflict_max_retries`	A file with the same name was being written at the same time. mxHERO retries.	No action needed unless it persists. Turning on overwrite for the rule avoids versioned names.
Event `storage_account_concurrent_lock`	The storage account has too many uploads running at once. The message is retried later.	For high volumes, add accounts and use load balancing. See Storage Load Balancing.
`rate_limit_error`, `rate_limit` (Egnyte, Dropbox)	The provider is throttling requests. mxHERO waits and retries.	No action needed unless it persists; then spread uploads across more accounts.
Large attachments fail on Box, Dropbox or Egnyte	These providers receive each file in a single request, so the provider's single-upload size limit applies.	Check the provider's limits for your plan.
`no_html_in_body` (warning)	The message has no HTML body, so no PDF of the body was created.	Expected behavior.
`STORAGE_USER_WITH_ERROR` (mailbox rules)	An account in a balanced pool was marked unhealthy and is skipped.	Re-authorize or replace the account.

Recipients cannot open the links

Symptom	Cause	Fix
Box link opens but the recipient has no access; event mentions `unshared_at`	The link expiration in your security definition is longer than your Box enterprise allows. The file is uploaded but not shared.	Shorten the expiration in the security definition, or change the Box enterprise sharing settings. See Recommended Box Settings.
Public links do not work (any provider)	The provider's tenant or folder settings do not allow public ("Anyone") links.	Allow the sharing level your security definition uses, or choose an organization or recipient link. See Link Security Options by Provider.
OneDrive or SharePoint recipient links fail; event `onedrive_guest_not_replicated`	mxHERO created an Entra B2B guest for the external recipient and the directory has not replicated yet. The message is retried.	Usually resolves itself. Your tenant must allow guest invitations and external sharing with guests.
Google Drive sharing fails with `cannotEditExpirationOnInheritedPermission`	The target folder inherits a permission that blocks the expiring share.	Store files in a folder without that inherited permission, or remove the expiration.
mxHERO Shares recipient sees "The file does not exist or has expired"	The link expired, was revoked or deleted, or the file was blocked as malware.	Check the share in the End User App, or the item in mxHERO Shares › Malware. See Malware Detection.
mxHERO Shares recipient sign-in code does not work	Codes expire 10 minutes after they are sent and work once.	Ask the recipient to request a new code.

Reprocessing messages that failed

Messages that could not be stored after all retries on archiving-type rules are kept for reprocessing. Open Rules › Reprocess Emails, pick the storage account and start reprocessing after you fix the cause. See Reprocess Emails.