Opened the book, thought "no, it can't be". Agonized for days and weeks if I'm making a fool of myself.
Sent the bug report.
First word in first sentence in first paragraph in first chapter was wrong. Got my cheque. ;-)
But the number of parameters is finite, and all parameters have a finite number of possible values.
His errata changed the wording thus:
Zillions of alphabets can be generated by the programs in this book. (https://ftp.rrze.uni-erlangen.de/ctan/systems/knuth/dist/err...)
I was so excited.
I then checked the errata. It was known.
It took another 20 years before I found an actual mistake, regarding the early history of superimposed codes. A very specialized topic where I have one of the few copies of the patent challenge distinguishing between random superimposed codes and arbitrarily selected superimposed codes.
I have a check.