I am trying to convert my old database to utf8 but mysql refuses because the
index cms_index_module_templates_by_module_name_template_name becomes more than
1000 bytes.
#1071 - Specified key was too long; max key length is 1000 bytes

The database was originally created with CMSMS 1.4 (or even older, don't
remember). It has over the years always been upgraded step by step to the latest
version 1.11 now.

In version 1.4b1 in the table module_template the fields module_name and
template_name are defined as VARCHAR (200) (see the 1.4b1
install/schemas/schema.php)
In version 1.5b1 the length in schema.php is reduced to C(160) for both fields.
This is probably done because of the index becoming too long in utf8, see also
http://forum.cmsmadesimple.org/viewtopic.php?t=15578
New databases work fine in utf8.

However: as far as I can tell, there has never been an upgrade step that reduces
the size of the fields. Therefore in my database the fields are still 200
characters causing the index to become too long.

Solution: an upgrade step should reduce the length of the two fields.