Well, it seems there's something wrong with the blueprints. Whether it comes from a uti, utd, utc or a 2da file is unfortunately not an immediate finding. Since it appeared "recently" though, what did you do lately? I suggest you sort the files in your directory by date, and move the blueprints (by batches of 10 for example, depending on how many there are) somewhere else starting from the newer ones, then restart the toolset: if the error is gone, then you'll know the culprit was in the batch you just moved. If not, the undo the move and start again with the next one.
It's also possible the problem comes from a 2da: to find out, try to open the last one you modified (within the toolset) and check if all the lines all have the same number of data (an extra space in a text field is enough to break the expected pattern).