The problem looks like below.
You do not have sufficient permissions to access this page
The supposed permission problem has occured before and mainly involves plugins. For older version of wordpress, your problem may be solved by one or both of the
- Change of table prefix - I suggest you visit this to solve that problem. And it also solves a string of other things, too.
- Failed Upgrade - If you used an automatic upgrade and failed, it is possible that the version number saved in the database is already updated. You can force upgrade it by updating the your version number. Another alternative is by using MarkAquit’s script here
However, these solutions are only applicable for older versions of WordPress. If you have a clean install, you should not encounter this. That’s why it didn’t work and was back to square one of investigation. Upon further checking, it turned out that the problem is related to old plugins. Apparently, there are plugins that was written before the current releases and whose parts of the code is no longer compliant with the current version of WordPress.
Finding the offending plugin is a bit tricky especially if you are using a lot of plugins. Luckily, I only encounter this in a contact page plugin and replace it accordingly with a new plugin which was released lately. The problem with my older plugin is that there’s no more active development. And so when some of the codes were deprecated, the plugin fails.
So what’s the problem then? Old Plugins.