Hi,
achessel wrote:But I am quite sure the application pool is setup for 32bit as described in the doc; beside it used to work fine until now and I did not change anything in the iis side of things.
Could it be that using 64bit python is what is causing the error? I tried putting '32bits=false' in the application pool thinking maybe everything is in 64 bits now, I get another error
'Failed to import callback module 'omero_web_iis The system cannot find the file specified.'
I have a clean install of OMERO with 64bit Python 2.6 and I didn't make the "Enable 32-Bit Applications" change for the same reason as yourself (compiled isapi_wsgi from python x64 as well). Setting "Enable 32-Bit Applications" to True in the Application Pool Advanced Settings _also_ breaks my OMERO.web. As you suggest, this is likely because we've both compiled a 64bit version of isapi_wsgi.
Definitely change this back to False and let us know how you get on.
Incidentally, when you received an Error 500, this may in fact have been OMERO.web working. If you see this, make a second (or subsequent) request after you see the Error 500 and OMERO.web should appear. This is caused by the interaction between the IIS worker threads sleep mode and isapi_wsgi.
We have a workaround for this issue, which will be in the next version of the documentation, which should make this initial Error 500 only ever appear on a server upgrade or IIS restart. [1]
[1]
https://trac.openmicroscopy.org.uk/ome/ticket/12504