I encountered that problem at table's creation time:
[Amazon](500310) Invalid operation: ----------------------------------------------- error: Maximum column length exceeds 255 code: 8001 context: Limit is due to use of text255 encoding query: 0 location: column.cpp:309 process: padbmaster [pid=12110] -----------------------------------------------
Quite mysterious at first glance but after a quick look at the created table, everything became clear. In fact, I wanted to create a table with a column much longer than used encoding:
CREATE TABLE ... ( too_long_field VARCHAR(500) NOT NULL ENCODE TEXT255 )
TEXT255 is an encoding helping to reduce the space for the columns in which some words occur very often. Common words will be represented as 1 byte and their definition will be put into a dictionary. However, only 245 unique values of a column will be stored there. The remaining entries will be uncompressed.
The error simply says that the column's length is too big in order to apply TEXT255 encoding. Reducing the length to 255 or less should help in that case. Or if not, using another encoding algorithm.