The secure sockets layer (SSL) certificate sent by the server was invalid and this item will not be crawled

On starting the full crawl of the default content source I received the  error. “The secure sockets layer (SSL) certificate sent by the server was invalid and this item will not be crawled”

It was because one of the site was SSL enabled. 

Solved it in the following manner,
1. Navigate to Central Administration.

2. Go to Application Management > Manage Service Applications and click on your Search Service.

3. In the left Navigation, click on “Farm Search Administration”

4. Under the Farm-Level Search Settings, click on Ignore SSL warnings status “NO” (by default is No). Select the Ignore SSL certificate name warnings check box if you want to trust that sites are legitimate even if their certificate names are not exact matches

  

5. Restart Incremental or full crawl as needed.

OneNote Sync Error Code: 0xE4020005

We were noticing OneNote Sync issues with SharePoint 2010 and below workaround worked for us,

1. Right-click section in question, Move or Copy...

2. Select another Notebook beside the one it resides in, Move.

3. Sync the changes.

4. Move the section back to the desired Notebook.

5. Sync the changes.