Hello @Patrick24000,
was the project already created in 1.4 version?
You can try this workflow (instead of deleting the component part delete the ortho part of the RCPROJ file): Loading Project: Invalid or corrupted input data - #2 by OndrejTrhan.
You will lost the created ortho, but it should be possible to open the project then.
Hi Ondrej, Thank you for the reply. That worked! I think the ortho projections had been created in 1.4 but before the file was saved in 1.4 format. Patrick