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Angular error NG05201 means an untrusted value reached a resource-loading URL, such as an iframe’s src. Find the binding or sanitizer call that supplies it. If the URL is not fully controlled by your application, do not bypass Angular’s check; validate the input or use a regular URL context that Angular can sanitize.
What NG05201 means
Angular distinguishes resource URLs from ordinary links. A regular URL can be sanitized—for example, Angular can remove a dangerous javascript: scheme. A resource URL can make the browser fetch and execute external content, so Angular cannot make an arbitrary string safe and rejects an untrusted value instead. See Angular’s NG05201 error reference.
The error can occur when a value is bound to these resource-loading attributes:
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It can also occur when code calls DomSanitizer.sanitize() with SecurityContext.RESOURCE_URL and a plain string. Angular’s reference demonstrates this with an https://example.com string; the URL’s HTTPS scheme does not by itself make the value trusted. See the error reference.
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How to find the value that triggers it
- Check resource URL bindings. Search templates for the attributes above, particularly bindings such as
<iframe [src]="userUrl"></iframe>. Trace the bound value back to where it is created and determine who controls it. - Check explicit sanitization calls. Search application code for
DomSanitizer.sanitize()andSecurityContext.RESOURCE_URL. Passing a plain string to that resource URL context can produce NG05201. - Classify the source. A fixed URL selected and controlled by application code is different from a URL supplied by a user, received from an uncontrolled service, or assembled from untrusted input. Do not treat a value as application-controlled merely because it currently looks like a familiar URL.
Choose a safe fix based on who controls the URL
If the URL is user-supplied or otherwise uncontrolled
Do not pass it through bypassSecurityTrustResourceUrl. That method does not sanitize, validate, or restrict a URL; it tells Angular to trust it. Angular warns that trusting a user-supplied resource URL can allow arbitrary content, including malicious scripts, to load. Reject or constrain untrusted input according to the application’s requirements, and use a regular URL binding when the destination belongs in a URL context Angular can sanitize.
If the URL is fully controlled by the application
Angular documents DomSanitizer.bypassSecurityTrustResourceUrl as an escape hatch for a resource URL the application itself controls. It returns a SafeResourceUrl that can be used in a resource URL binding. Use it only after establishing that the value is trusted by design:
import { DomSanitizer, SafeResourceUrl } from '@angular/platform-browser';
const trustedResourceUrl: SafeResourceUrl =
sanitizer.bypassSecurityTrustResourceUrl('https://example.com/embed');In this example, sanitizer is an injected DomSanitizer. The trust call is an assertion, not a security check. Do not substitute a value that came from a user or another uncontrolled source. Angular explains this distinction in its NG05201 guidance.
Why a plain HTTPS URL may still fail
The scheme answers how a URL is addressed; it does not establish that external content is safe to load in a resource context. Angular’s resource URL policy is about the consequences of loading the destination, not just whether the string begins with https://. A plain string therefore remains untrusted in a resource URL context unless the application deliberately marks a controlled value trusted.
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Angular version note
Angular’s official NG05201 reference was accessed on October 7, 2026, and its rendered page identifies Angular v22.2.1 build fa63bfa. The page does not state a publication date. Documentation and behavior can change across releases, so consult the error reference for the Angular version used by your application.
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