It should not be necessary to explicitly migrate anything on upgrading to version 3.6, but note 
that the following behaviour is changed as default:

(1) Missing files

In the case where a file is present as a standard file in the test case directory,
but not generated by the test, this will be explicitly classified as a 'missing file'.
Also, when collating other generated files, auto-generated files saying that the file
could not be found are no longer created.

So, if you have files that are old lying around, you'll need to remove or rename them. Likewise,
if you ever saved any such auto-generated error files, you'll need to remove them too. This
should be possible by just running the tests and pressing Save as appropriate.

(2) Test Suites Containing entry in the Select dialogue (-ts flag on command line)

The mechanism for requesting test suites has confused a few people in its time. It therefore
now operates on the whole test suite path rather than on each level separately. This probably
simply makes it more intuitive, but if you've got used to old behaviour you may find it
doesn't do the same thing any more.

(3) Catalogue functionality will now also report file edits as well as creation and deletion

So you might get some differences in catalogues on running with version 3.6 and later. Should
be OK to just save them.

(4) Default text comparison tool on Windows is now 'diff' (as on UNIX)

Diff is installed by default anyway if you've installed tkdiff. It performs much better on larger 
files.

If you used and liked ndiff.py you'll need to set 'text_diff_program:ndiff.py' to maintain the
behaviour.

(5) Dynamic GUI now collapses entirely successful test suites automatically

This has generally been thought to be a good change, but the possibility is there to turn
it off if you don't like it. Set auto_collapse_successful:0 to preserve the old behaviour.
