Hi! I am facing the same problem. My WordPress has got updated by itself from the 4.9 version to 5.0 version. I was not aware of that how it happens.
& today I saw that I can’t edit my existing posts or pages. Even I can’t create new post or pages.
Once I clicked on my content in my posts, it is showing below mentioned things.
“The editor has encountered an unexpected error.
Attempt Recovery, Copy Post Text, Copy Error”
Why it is happening? Please help.
