After install on Backdrop, I get "Oops! Incorrect CiviCRM version. This installer can only be used for the Drupal version of CiviCRM"
I am installing 5.4.0 into Backdrop 1.10.1. The download file is civicrm-5.4.0-backdrop.tar.gz and when I start to install it shows the correct version in the upper right of the installer. The install completes okay. But when I then get "Oops! Incorrect CiviCRM version. This installer can only be used for the Drupal version of CiviCRM."
At that point the Backdrop site no longer bootstraps.
A reply on StackExchange suggested ( https://civicrm.stackexchange.com/questions/26253/ )"I recently got this when i was trying to install drupal and it said 'This installer can only be used for the Backdrop version of CiviCRM'. Clearing up Drupal and CiviCRM caches fixed the problem for me." However that has not resolved the problem.