What this family covers
Fifteen named faults, all raised by Config\ConfigurationError, all about the fields on a server entry, a product's configurable options, or the region a given order actually resolves against. See "Connecting Your Own IDrive e2 Account" and "Setting Up a Storage Product" in this category for where each of the fields named below actually lives.
The Password field: a real token, a shaped-but-wrong value, or WHMCS's own mask (four codes)
token_missing and padded_token are the simplest of the fifteen: the field is empty, or has whitespace a copy-paste left behind. token_malformed means something is there but is not shaped like a reseller token at all. credential_is_a_mask deserves the most care: it means the Password field currently holds WHMCS's own password mask — not a weak or wrong credential, but no credential at all — and because saving a server entry re-posts a masked field, the real token underneath is already gone and nothing on file will recover it. Re-enter the real token from the vendor and save; every customer under this reseller account is affected until you do.
The Access Hash field, and why a mask there means something different (two codes)
access_hash_is_a_mask is the mirror of the Password-field mask above, and is kept as its own code on purpose: this field is not a secret at all in this module's design, so a mask here means "clear it or re-enter the non-secret override JSON it is meant to hold" — there is nothing to revoke. secret_in_plaintext_field is the opposite finding: a credential-shaped value was found sitting in this field, which WHMCS stores in plaintext. Move it to the encrypted Password field, then revoke and reissue that token, because it has been readable in every database backup taken since it was entered.
The white-label domain and the API base (three codes)
whitelabel_domain_missing and whitelabel_domain_invalid both concern the Username field — this brand's own domain, with no fallback to anything else. api_base_invalid concerns the Hostname field; leave it blank to use the vendor's own default, or correct it to a bare hostname with no scheme, path or port.
Regions, tiers and which source an order actually reads (five codes)
region_code_invalid and credential_missing_for_region are both about a specific region: an unusable code, or no access key minted for it yet (a key from one region is never valid in another). region_option_missing and tier_option_missing both mean the product itself declares nothing for the customer to choose from — add the missing configurable option group. region_source_unresolved is the one code standing in for a family of six underlying reasons: an attached addon reads its region from the server entry's Access Hash, while a standalone product reads the customer's own option or the "Default Region" module option, and any of those sources can be unset, malformed, or name a region this reseller account does not serve. The message this code carries always ends with a tag naming which source and which reason, so grep for the tag rather than the reworded sentence around it.
The one that is not a mistake to fix (one code)
addon_path_not_offered is deliberate and reversible, not a bug: storage is sold as a standalone product in this version, because a WHMCS product addon has nowhere to carry a region or a quota at all. If you attached this module to a product addon, the fix is to sell it as its own product instead — see "Setting Up a Storage Product" for the shape this module expects.