Error Message: No validated OPDS content, click here to see what's OPDS Catalog

[Robert N Chandler]

1. Calibre 2.67 [64-bit]
2. Windows 10 Professional [x64]

Reproduction steps:

1. Open eBook reader - Multiple readers tested.
 a. Moon+ Reader PRO
 b. Aldiko
2. Connect to local library - CALIBRE server
 a. Connection made internally
     1. Results: No validated OPDS content, click here to see what's OPDS catalog.
                  500 Internal Server Error
                  The server encountered an unexpected condition which prevented it
                  from fulfilling the request.
                  Powered by CherryPy3.2.2
 b. Connection made externally
     1. Results: No validated OPDS content, click here to see what's OPDS catalog.
                  500 Internal Server Error
                  The server encountered an unexpected condition which prevented it
                  from fulfilling the request.
                  Powered by CherryPy3.2.2
3. I have tested this on two different devices [Amazon Kindle FIRE and Lenovo MOTO G4]. I can connect to the catalog via HTML if I leave off the "/OPDS" flag, but as of last night I was unable to connect to the OPDS library. I have been utilizing Calibre since ver. 0.8.31 [64 bit since 0.9.26], and this is the first problem I have ever had with the product. I hope that I have provided enough information to be of assistance; if I can provide any further or can assist with further troubleshooting please contact me at my EMail address listed.