The solution to the failure to read channel information when dedecms generates a message in the background

Failed to read channel information, follow-up operations cannot be performed!

That's because there are documents that use the content models and columns added before, but the content model is deleted, and the documents are still there. When generating the whole site or generating the document, it will prompt "Failed to read channel information, unable toFollow up!"
Solution
Let's let the program tell us which document is the problem
Open /include/channelunit.class.php and find, about line 35

$this->dsql = $GLOBALS['dsql'];

Add below it

echo $cid."-".$aid;echo "
";

As shown

After adding it, re-generate it to see which document is prompted

Let's look in the list of all files

Just delete the problematic document.
If the final build is OK, delete the line of code you just added in /include/channelunit.class.php.