What if HTML editor in TYPO3 does not work in Chrome

Due to an Chrome update (73) the RTE editor does not work anymore.

I have fixed it in TYPO3 6.2.X by editing:
typo3/sysext/rtehtmlarea/htmlarea/htmlarea.js

Change this:

src: Ext.isGecko ? 'javascript:void(0);' : (Ext.isWebKit ? 'about:blank;' : HTMLArea.editorUrl + 'Resources/Public/Html/blank.html')

To this (tested on Chrome version 91.0.4472.106):

src: Ext.isGecko ? 'javascript:void(0);' : (Ext.isWebKit || Ext.isChrome ? '' : HTMLArea.editorUrl + 'Resources/Public/Html/blank.html')

Old lines that worked on Chrome 73, but no longer on 91+:

src: Ext.isGecko ? 'javascript:void(0);' : (Ext.isWebKit ? (Ext.isChrome ? 'about:blank;' : 'javascript: \'' + HTMLArea.htmlEncode(this.config.documentType + this.config.blankDocument) + '\'' ): HTMLArea.editorUrl + 'Resources/Public/Html/blank.html')

If this does not fix your issue try replacing the line with:

src: Ext.isGecko ? 'javascript:void(0);' : (Ext.isWebKit ? 'javascript: \'' + HTMLArea.htmlEncode(this.config.documentType + this.config.blankDocument) + '\'' : HTMLArea.editorUrl + 'popups/blank.html')

If you cannot find the code then you use an older version of TYPO3. In that case replace this:

src: UserAgent.isGecko ? 'javascript:void(0);' : (UserAgent.isWebKit ? 'javascript: \'' + Util.htmlEncode(this.config.documentType + this.config.blankDocument) + '\'' : HTMLArea.editorUrl + 'Resources/Public/Html/blank.html')

With this:

src: UserAgent.isGecko ? 'javascript:void(0);' : (UserAgent.isWebKit ? 'about:blank;' : HTMLArea.editorUrl + 'Resources/Public/Html/blank.html')

In newer TYPO3 7 versions this works:

src: UserAgent.isGecko ? 'javascript:void(0);' : (UserAgent.isWebKit ? (UserAgent.isChrome ? 'about:blank;' : 'javascript: \'' + Util.htmlEncode(this.config.documentType + this.config.blankDocument) + '\'' ): HTMLArea.editorUrl + 'Resources/Public/Html/blank.html')

For TYPO3 7 adjust this file:
typo3/sysext/rtehtmlarea/Resources/Public/JavaScript/HTMLArea/Editor/Editor.js

Important note. In TYPO3 7 the cache can be sitting in your way. Make sure you test it in Incognito mode. When it is working you can flush the cache by opening the view source of the iframe and then press CTRL-F5 to reload the page.