#fields 13 articles

• "Invalid text value" (HTTP 500) means a Text column hit its 255-character limitgotchas / rest-apiGeneric 500 naming no field; a Text column capped at 255
• fields/getbyinternalnameortitle returns 400, not 404, for a missing fieldgotchas / rest-apiIt throws ArgumentException (HTTP 400), not 404; an existence-check that hard-fails on non-404 breaks the "field missing → create" path, and one that creates on any non-200 duplicates the column when throttled
• $filter on a multi-value person field can return 400 — filter those client-sidegotchas / rest-apiFall back to client filtering, but only on HTTP 400
• A column called MyField0 appears — a throttled existence check or two web parts provisioning at oncegotchas / rest-apiPOST /fields with a taken name succeeds with a numeric suffix; 429 read as "missing", a cached check or two concurrent web parts each make a twin — three-state check, single run per site, name check after the create
• A Hyperlink column takes an object, not a stringgotchas / rest-apiIt reads back as { Description, Url } ([object Object], React #31) and a plain string fails the whole save with 400; one helper each way, 255-character address limit, scheme allowlist
• A new Choice value in your provisioning code never reaches already-deployed sitesgotchas / rest-apiCreate-if-missing never updates an existing field; a new Choice value in the manifest no-ops on deployed sites; reconcile with a post-hook SP.FieldChoice MERGE (plain JSON with @odata.type under SPHttpClient) that only…
• Choice fields accept any value over REST — validation is a form-only illusiongotchas / rest-apiREST skips choice validation entirely; enforce vocabulary yourself
• FieldValuesAsText re-encodes underscores in JSON keysgotchas / rest-apiA_x0020_B comes back as A_x005f_x0020_x005f_B; decode _x005f_ before matching
• Looking up a field that does not exist returns 400, not 404gotchas / rest-apifields/GetByInternalNameOrTitle on a missing field answers 400; test existence with a $filter instead
• Lookup and person fields — read with $expand, write with <Name>Idgotchas / rest-apiRead via $expand + projections, write via Id; ~12-lookup query limit
• Multi-line text in a document library stops at 255 charactersgotchas / listsA REST MERGE stores 70k characters, but ValidateUpdateListItem rejects anything over 255 unless the column has UnlimitedLengthInDocumentLibrary – set it at creation or PATCH it later
• POST /fields rejects a subtype property like RichText unless the body names the subtypegotchas / rest-api{ FieldTypeKind: 3, RichText: false } without @odata.type is read as SP.Field and fails with 400 – plain text columns in the same loop succeed, so the list ends up half-built; use CreateFieldAsXml or annotate the type
• Telling a list's own columns from inherited ones — Hidden is not enoughgotchas / rest-apiHidden is not enough; FromBaseType + CanBeDeleted are what separate the list's own columns