Matrix Error - "Field Limit is too big for your chosen Column Type" I have a matrix field which is used a my main Body content field.
The site has just been updated to the latest version of Craft and I tried to add a block to the matrix field but when i try to save it I get the error on a plain text field: 

Field Limit is too big for your chosen Column Type.


Even if i open the field and don't make any changes and jut save it I get the same error. The matrix field has 11 Block Types.  

I have the same field in another website which actually has another couple of blocks in it and it can save without any issues.   

I have found this thread: https://github.com/craftcms/cms/issues/2009 
and possibly related to a MySQL issue.

But is the issue related to the size of the Matrix Field? Or overall the number of fields in the database?
But is the issue related to the size of the Matrix Field? Or overall the number of fields in the database?


Neither. :)

That error message isn't related to the linked Github issue (although I can see how you'd get them confused).

It's coming from the Craft's Plain Text field type: https://github.com/craftcms/cms/blob/develop/src/fields/PlainText.php#L126-L137

There's a discrepancy between one of the Plain Text field's settings in your Matrix field where the charLimit setting on the field is greater than the database Column Type setting for that field can hold (i.e. for MySQL varchar, text, mediumtext, etc.).