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bug: During hydration Angular expected a text node but found a comment node. #30125
Description
Prerequisites
- I have read the Contributing Guidelines.
- I agree to follow the Code of Conduct.
- I have searched for existing issues that already report this problem, without success.
Ionic Framework Version
v8.x
Current Behavior
Following from #28625
My only HTML file is: app.component.html
<ion-label>Home</ion-label>provideServerRendering() causes
ERROR RuntimeError: NG0500: During hydration Angular expected a text node but found a comment node.
Fully:
RuntimeError: NG0500: During hydration Angular expected a text node but found a comment node.
Angular expected this DOM:
#text(Home) <-- AT THIS LOCATION
…
Actual DOM is:
<ion-label _ngcontent-ng-c982784965="">
<!-- --> <-- AT THIS LOCATION
…
</ion-label>
Note: attributes are only displayed to better represent the DOM but have no effect on hydration mismatches.
To fix this problem:
* check the "_AppComponent" component for hydration-related issues
* check to see if your template has valid HTML structure
* or skip hydration by adding the `ngSkipHydration` attribute to its host node in a template
Find more at https://angular.dev/errors/NG0500
at validateMatchingNode (core.mjs:15140:11)
at locateOrCreateTextNodeImpl (core.mjs:30741:16)
at Module.ɵɵtext (core.mjs:30715:22)
at AppComponent_Template (app.component.html:4:12)
at executeTemplate (core.mjs:12849:5)
at renderView (core.mjs:14018:7)
at renderComponent (core.mjs:13964:3)
at renderChildComponents (core.mjs:14064:5)
at renderView (core.mjs:14046:7)
at ComponentFactory.create (core.mjs:17381:9)Expected Behavior
provideServerRendering should work with no issue.
Steps to Reproduce
- Clone https://github.com/sign/translate
- Edit
app.component.htmlto include only<ion-label>Home</ion-label> - Edit
app.config.server.tsto includeprovideServerRendering() - Run
npm start
Code Reproduction URL
https://github.com/sign/translate
Ionic Info
[WARN] You are not in an Ionic project directory. Project context may be missing.
Ionic:
Ionic CLI : 7.2.0
Utility:
cordova-res : 0.15.4
native-run : 2.0.1
System:
NodeJS : v22.0.0
npm : 10.5.1
OS : macOS Unknown
"@ionic/angular": "8.4.1",
Additional Information
Blocks sign/translate#194 and angular/angular-cli#29236
Activity
LBZC4600 commentedon Apr 27, 2025
Hi, what about this issue?
thetaPC commentedon Oct 7, 2026
Thanks for the report, and sorry for the delay.
Verified on 9.0.7.
ion-labelputs an empty placeholder comment before its text so it can position slotted content. WithprovideClientHydration()on, Angular walks the server-rendered DOM, expects the text nodeHomefirst and finds that comment instead. #30958 fixed this as a side effect: it made Ionic hide the comment from DOM traversal, and it shipped in v8.7.18. The setup in this issue (standalone components,provideServerRendering()with noIonicServerModule) now hydrates without errors, including on a full page with a header, toolbar, content and list.@ionic/angularto 8.7.18 or later.Angular's client hydration is still not supported in two other setups, which throw
NG0500orNG0502on 9.0.7:IonicServerModulefrom@ionic/angular-server.IonicModuleinstead of standalone components.In both cases, skip hydration for the Ionic tree by adding
ngSkipHydrationtoion-app:ngSkipHydrationonly works on a component's host element, soIonApphas to be in the component'simports(or come fromIonicModule). Angular then renders everything insideion-appagain on the client instead of reusing the server DOM.Closing this as fixed in 8.7.18.