Sorry for delay reply but few days back, I encoutered an issue and I was not able to view a post, it was showing a error, then I edited another post and updated it and then that post started showing same error and not not opening anymore.
I contacted my hosting customer care and they tried to resolve the issue by adding -d to the plugins folder and all plugins got disabled and now the post was opening perfectly.
So, they recommended me then to install the plugin one by one from my side and see which are causing the error and in my check as I activated the Easy TOC, it again shown the same error.
I don’t know the conflict but I had to deactivate the plugin, It was my fav because of the Active feature.