I think I have found the reason...
In build 120405 the JSON string has an extra space (x20) just after the {
eg:

[{ "title"......
5b7b20227469746c6522

and the earlier build did not add the extra space eg:
[{"title"......
5b7b227469746c6522

If the space is missing the latest build cannot interpret the JSON code and corrupts the database when saving.

Those look like EM errors. There must be JSON encoding that does NOT have an extra space next to the opening and closing curly braces. Thus, EM thinks it is an expression and shows syntax errors around the colons.

JSON must be passed through this for EM to avoid trying to parse it:

str_replace(array('{','}'), array('{ ', ' }'), $json)

I'd be very surprised if JSON can't cope with the internal space - but perhaps someone can check that on some other JSON code.

I may be wrong but after a quick look at the code, Limesurvey uses it's own JSON decoding which may work differently to standard php.

The quick fix is to update the database with a replace function:
UPDATE TABLE_NAME SET FIELD_NAME = REPLACE( FIELD_NAME , '[{"', '[{ "' ) WHERE 1
using MYSQL

Tac, do you recall which older version of 1.92 you were using for your original tests?

Also, when using that older version, did you try going through the same steps (executing the same survey with the same token) - and if so, did it fail there too?

I think the build was 120311, and I had no problem with modifying/viewing previously uploaded files. (the JSON code had no extra space then)

I'm using LS in a slightly unusual way, members are allowed to update their info but filling out a survey (additional invites are sent of request). The info then populates a tourism website and displays member information.

Now after upgrading, the extra space(s) is needed to execute the survey more than once. (If a brand new survey is executed there is no problem)
To test, just remove the extra space directly in the database table.

Extra spaces must be allowable in JSON. See examples here (http://en.wikipedia.org/wiki/JSON) and here (http://json.org/example.html).

So, the core problem is probably a little different.

Tac-

I'm having trouble replicating a variant of this. If I use the current build, I can upload some pictures, resume later, and see the pictures again. The values in the database are correct, and editing of images is fine.

There was a bug in browsing of individual responses, but I just fixed that.

Is manipulating images working OK for you on the current version? Does this issue only occur when upgrading from a prior version?

Fix committed to master branch: http://bugs.limesurvey.org/plugin.php?page=Source/view&id=8112

Correct! You can upload pics and edit them later with the current build. But if you have records in the database of uploaded files from the previous build, there is a problem as evidenced above.
You can replicate quite easily - just use the new build to upload some files via a survey question. (Set the global settings to allow updating of survey questions)
Then use Mysql to view the record and in the field where the JSON record is stored, observe the space just after the {. If you remove the space and then try to view/update the same survey record, you get those red syntax errors and garbled info, no images and the database record gets corrupted.

Tac-

I think that patch should fix it, but since I couldn't replicate the the problem, can you test it?

Our notes crossed paths. Just tried the Mysql approach you mentioned and view/update the same record works fine with the latest patch (and the database record gets fixed)

Thanks TMS, I will test it and let you know.

Confirmed TMS, this is now resolved. Even JSONs without the extra space are being decoded correctly. Thanks for your help.
I have posted another issue which is related to the latest version. An easy fix I think.

New 1.91+ version released.

Fix committed to Yii branch: http://bugs.limesurvey.org/plugin.php?page=Source/view&id=8173