Hi - I hope I haven’t missed a previous thread on this… but I have tried on two Pro 1.2.3 sites to add and activate Revolution Slider both times I get this issue, I have tried on PHP 7.0 and 7.1 running on Digital Ocean.

I am working around it by using an older version, but obviously not ideal.
10.20.17 Update: reverted to pre Pro 1.2.3 also moved back to PHP 7 and was able to activate Revolution Slider and get into the page builder again. Wondering if Digital Ocean, although giving the option for 7.1 was not really running it. Anyway I think I am good for now.