I have the same error "WordFence API error: An error occured trying to open the requested file."
after each wordfence scan.
The last concerned files were :
- wp-content/plugins/wysija-newsletters/views/front.php
- wp-content/plugins/wysija-newsletters/views/back/campaigns.php
I checked with winmerge and see very few differences.
Also, wordfence send me an email untilted "Modified plugin file".
And when I clic "See how the file has changed" I have got : "There are no difference between the original file and the file in the repository." !
This was for "plugins/google-analytics-dashboard-for-wp/readme.txt"