[Mozilla Enterprise] CCTK xpi install fails - 'does not contain a valid manifest'

[Chris Mortimer]

Having read that Firefox ESR 68 supports 2.4 of CCK2 I upgraded my Firefox to ESR 68, download CCTK 2.4 from https://github.com/mkaply/cck2wizard/releases/tag/2.4 but am having trouble installing it.  I've tried:

- From Firefox File menu > Open File.  Locate and open the XPI file and, Firefox complains that 'This add-on cannot be installed because as it appears to be corrupt'

- From within about:debugging > Load Temporary Add-on.  Load the CCTK xpi file, Firefox shows in a red rectangle 'There was an error during installation: File C:\tmp\cck2wizard-2.4.xpi does not contain a valid manifest'

Am I doing something stupid or is there a problem?

Chris Mortimer - Computer Associate
Dept of Applied Mathematics, CMS
University of Cambridge. CB3 0WA. UK.