We have had troubles updating site icons in SharePoint Online. It might be related to one of the following:

• It occures only on hub sites
• The sites have a custom theme

The error message:

We experienced a problem updating the icon. Please try again in a few minutes.

But what I found is that there are two places where you change the site icon. If the first does not work, try the second one, that was what worked for us:

While trying to set up a new Home Site, I discovered that there is a tool (browser extension) called Page Diagnostics for SharePoint.

After running this, I tried that command again and it was smart enough to detect the problem the tool discovered.

Also Network Trace is available.

Network trace

Page Diagnostics Tool is defnitely a tool to have in the troubleshooting toolbelt for SharePoint.

Setting up a Home Site

Here is the script:

This is my personal list of links and thoughts on troubleshooting performance in SharePoint Online.

Resources

• @MSFT365Status, a twitter flow on the incidents and resolutions
• connectivity service
• Service Status (open for all), Service Health (for admins)

Health info in Response Headers

Every response from SharePoint Online contains some health information:

• Diagnosing performance issues with SharePoint Online (MSDocs)
• Troubleshooting SharePoint Performance Issues with F12 (blog post)

Following Response Headers could reveal the health:

I troubleshooted a piece of CSOM code in SharePoint 2013. I got the following error:

Method “GetList” does not exist

The reason was that the method GetList was not imlemented until March 2015 CU (15.0.4701.1001), and the SharePoint farm I had was SharePoint 2013 SP1 (15.0.4569.1000). So the solution is to install the Cumulative Update or use web.Lists.GetByTitle. GetByTitle has one aweful shortcoming: it doesn’t work in multilingual environments. So I have recommended to install the March 2015 CU.