I am seeing this error what does it mean? Update failed for sku in line  with a variant 
Best to use the debug route if you are w developer
In the above case we found that the error was because the variant we were updating had a 0 value in the weight therefore was rejected by shopify as it is a required field. We also found the weight unit had to be kgs or lbs
A solution is to simply blank out the mapping for the specific product field
Each connection you create on the DSYNC canvas between different endpoints keeps recent history which can be inspected to gain further insight into the request and response.
Accessing a debug route for a link is simple. First, you need to find the job ID for the particular connection you are interested in. This can be done through the job's history. Select the link on DSYNC canvas. You should see a HISTORY section at the bottom of the right sidebar which details statuses of recent synchronizations. Underneath the history records you notice the 'Show more...' link. Click on that link and note the URL in your browser. It should look something like this "https://app.dsync.com/#/portal/history/job/8888". The last part of the URL is the Job ID you need to access the debug route.
The debug route can be accessed by visiting the following URL: https://api.dsync.com/u_debug/job/<job_id>. Simply substitute the <job_id> placeholder for your actual Job ID. From our example above, the URL would be https://api.dsync.com/u_debug/job/8888
You must be logged in to your DSYNC account to access the debug route for one of your jobs.