[Steven Zahm]

@ valli

Can you switch to the non-custom Slim Plus to see if the error persists? If it does not, then there was a change that is not likely compatible with the newer versions of Connections.

If you do not have a copy of the non-custom Slim Plus, I see you have Tile Plus and Market too, can you try switching to them.

Lastly, I see files for Tile Plus and Market are being loaded from the following folder:
../wp-content/connections_templates/

I suggest deleting the market and slim-plus folders from within that folder. Only custom CSS files and custom template override files should be in that folder. My guess is that the legacy template installer was used trying when trying to install them originally.

Hope that helps, let me know what you find out.