I'm running a pool for some friends and myself, where we mine both dogecoin and litecoin (and occasionaly some other flavor of the day). The farms are pointing to a simple proxy: a C daemon that is connected to the stratums for easy socket switching.

When switching from one coin to the other, the stratum server immediately throws "Share is above target" errors. When it switches back to the original coin, all shares are accepted again

Exactly what causes the 'share is above target' error? Based on the logs below, is there a problem with the mining software or with the stratum sending the wrong data?

Both stratums are configured with a fixed diff level, vardiff is disabled. Here's a log of data going back and forth between a mining farm and server

step 1/5: litecoin stratum sends work to mining farm

{"params": ["ed84", "716a78103f53858c8baadc8179bdbc3012c981db2a41b552998cdc06b6bae287", "01000000010000000000000000000000000000000000000000000000000000000000000000ffffffff27034f0f08062f503253482f04398b1c5308", "0d2f7374726174756d506f6f6c2f0000000001a078072a010000001976a914238e80769414592ed96192e13cddf78953e84ff388ac00000000", ["a346c6f74e37f6528e9d34e35c530a79bf11487d5c9404574972ac652331943f", "117086b6331ecef97572a981b1d2a7baf269b163a0c252c03a9f8b93cf1fdc03", "fef9b6758f809b998ce072d7bddefa86657dbee2d0fe1d71fd8a6a5558fa4dce", "7caa16ac719103ea85494bf15ec0b27507fb7367b36c01ccea2151f2eebdc811", "bdf9a2879e8cee859d2510fa63c57411f5b2e32fe0e237f597d28e6add7a9923"], "00000002", "1b0dd506", "531c8b3c", true], "id": null, "method": "mining.notify"}

step 2/5: mining farm sends 6 valid shares to litecoin stratum

{"params": ["FarmOne", "ed84", "04000000", "531c8b3c", "fef81f01"], "id": 2, "method": "mining.submit"}
{"error": null, "id": 2, "result": true}
{"params": ["FarmOne", "ed84", "01000000", "531c8b3c", "c97a2601"], "id": 3, "method": "mining.submit"}
{"error": null, "id": 3, "result": true}
{"params": ["FarmOne", "ed84", "02000000", "531c8b3c", "685efb00"], "id": 4, "method": "mining.submit"}
{"error": null, "id": 4, "result": true}
{"params": ["FarmOne", "ed84", "01000000", "531c8b3c", "bacb9201"], "id": 5, "method": "mining.submit"}
{"error": null, "id": 5, "result": true}
{"params": ["FarmOne", "ed84", "04000000", "531c8b3c", "a221ad01"], "id": 6, "method": "mining.submit"}
{"error": null, "id": 6, "result": true}

step 3/5: system redirects mining farm to dogecoin stratum at this point

step 4/5: dogecoin stratum sends work to mining farm

{"params": ["2610", "bca4622ca0307fc2e3c2398f67b36a0d908306f62cc65761761c2faf1b488be8", "01000000010000000000000000000000000000000000000000000000000000000000000000ffffffff2703fd0802062f503253482f04658b1c5308", "0d2f7374726174756d506f6f6c2f000000000100f473ed742b00001976a914c8b32869360584a4876c7d7617142e0f8dc4404988ac00000000", ["2adb1eabd5c3fcabeb5f75c073e6009dee136a3cf0ba6b6082a7ad2f8fe2a070", "1061486e8cebb27914e7d3e24c0ce90e8b1fc0606cb1bf8f4cc61c4e4dbad84d"], "00000002", "1b527845", "531c8b67", true], "id": null, "method": "mining.notify"}

step 5/5: mining farm sends shares to dogecoin straum, but they are are above target

{"params": ["FarmOne", "2610", "04000000", "531c8b67", "f4be2e00"], "id": 7, "method": "mining.submit"}
{"error": [-2, "Share is above target", null], "id": 7, "result": null}
{"params": ["FarmOne", "2610", "01000000", "531c8b67", "45ca4700"], "id": 8, "method": "mining.submit"}
{"error": [-2, "Share is above target", null], "id": 8, "result": null}

Thanks!