What causes "Thenable self-resolution" in OrchardCMS/OrchardCore?

Never return deferred.promise() from a handler attached to that same deferred; return a new $.Deferred().promise() or a plain value

OrchardCMS/OrchardCore · error · TypeError

Thenable self-resolution

Error message

Thenable self-resolution

What it means

The slim build has the same Deferred implementation: it throws TypeError('Thenable self-resolution') when a handler attached to a deferred returns that deferred's own promise, which would violate Promises/A+ 2.3.1 by making a promise resolve to itself.

Solutions

Never return deferred.promise() from a handler attached to that same deferred; return a new $.Deferred().promise() or a plain value
Return a different thenable or value to continue the chain
Flatten the chain using .then returning plain results
Migrate to native Promises which report cycles via rejection instead

Example fix

// before
var d = $.Deferred();
d.then(function () { return d.promise(); });
// after
var d = $.Deferred();
d.then(function (v) { return $.Deferred().resolve(v).promise(); });

Defensive patterns

Strategy: type-guard

Validate before calling

null

Type guard

function isSelfReturn(returned, deferred) { return returned != null && typeof returned.then === 'function' && returned === deferred.promise(); }

Try / catch

try { d.then(handler); } catch (e) { if (e instanceof TypeError && e.message === 'Thenable self-resolution') { console.error('Deferred handler returned its own promise'); } else { throw e; } }

Prevention

Never return the same deferred's promise from its own handler
Return plain values or newly created promises in .then callbacks
Use native Promises for new chains to get clearer cycle detection
Audit shared deferred variables across chained handlers

When it happens

Trigger: Returning the same deferred.promise() from within a .then/.done/.fail handler on that deferred, e.g. `var d = $.Deferred(); d.then(() => d.promise());`.

Common situations: Promise chains refactored so a handler returns the closure variable holding the original deferred; helper functions that return the deferred they are chained on; accidental reuse of a single deferred across chained calls.

Understand the failure class

Background: "Invalid state transition" errors: "status must be X, actually Y", "already rejected/charging/uninstalled", "cannot ... while running" — what they mean when a library rejects your call — this error's family across 31 libraries.

Related errors

AI-assisted analysis of OrchardCMS/OrchardCore@4306c0717f (2026-09-13). Data as JSON: /api/errors/77564de76ed93468. Report an issue: GitHub.

Appendix: source

Thrown at src/OrchardCore.Modules/OrchardCore.Resources/wwwroot/Vendor/jquery-3.4.1/jquery.slim.js:3562

						return function() {
							var that = this,
								args = arguments,
								mightThrow = function() {
									var returned, then;

									// Support: Promises/A+ section 2.3.3.3.3
									// https://promisesaplus.com/#point-59
									// Ignore double-resolution attempts
									if ( depth < maxDepth ) {
										return;
									}

									returned = handler.apply( that, args );

									// Support: Promises/A+ section 2.3.1
									// https://promisesaplus.com/#point-48
									if ( returned === deferred.promise() ) {
										throw new TypeError( "Thenable self-resolution" );
									}

									// Support: Promises/A+ sections 2.3.3.1, 3.5
									// https://promisesaplus.com/#point-54
									// https://promisesaplus.com/#point-75
									// Retrieve `then` only once
									then = returned &&

										// Support: Promises/A+ section 2.3.4
										// https://promisesaplus.com/#point-64
										// Only check objects and functions for thenability
										( typeof returned === "object" ||
											typeof returned === "function" ) &&
										returned.then;

									// Handle a returned thenable
									if ( isFunction( then ) ) {

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