I play with 2 friends and we get alot of desyncs too.
In our latest logs: CS_FLEET_PATH: [289325 - 4294595492] <<< Mismatch! But we had POP_MODIFERS too. One of my friends found 'File 'mod/ugc_911635167.mod' should be in utf8-bom encoding (will try to use it anyways)' so he's reinstalling now. We had this since 2.0 (with no mods enabled).
Every game desyncs and becomes unplayeble at some time (fleet not moving, broken auto explore etc.)
Edit (running 2.05 now and tried all beta's and patches):
Some other errors:
Invalid contact location for first contact
country scope contains invalid object at file:
common/scripted_triggers/00_scripted_triggers.txt line: 559
common/diplo_phrases/00_diplo_phrases.txt line: 19130
fcommon/diplomatic_actions/00_actions.txt line: 1007
Script Error: Invalid context switch[event_target:rebel_country], file: events/unrest_events.txt line: 1482
After a fresh installation of Stellaris (2.0.5 Beta) we could play it for about a hour without desyns. Now again we have the POP_MODIFIER desync. With the following messages in de error.log
[22:58:33][bitmapfont.cpp:2827]: Could not find coloring for character ' '
[22:58:33][bitmapfont.cpp:2827]: Could not find coloring for character ' '
[22:58:33][bitmapfont.cpp:2827]: Could not find coloring for character ' '
[22:58:33][bitmapfont.cpp:2827]: Could not find coloring for character ' '
[22:58:33][bitmapfont.cpp:2827]: Could not find coloring for character ' '
[22:58:33][bitmapfont.cpp:2827]: Could not find coloring for character ' '
[22:58:33][bitmapfont.cpp:2827]: Could not find coloring for character ' '
[23:06:04][gamestate.cpp:2354]: POP_MODIFIERS: [26808574 - 26808774] <<< Mismatch!
Also we see some other messages in the error.log not related (I think) with the desync:
[21:19:28][government_restrictions_solver.cpp:765]: Result civic [civic_great_khans_legacy] is not valid
[21:30:48][country.cpp:11515]: Invalid contact location for first contact between Tebadoran Star Technocracy and Grim Souls
[21:30:48][country.cpp:11515]: Invalid contact location for first contact between Bothrian Blessed Assembly and Grim Souls
[21:30:48][country.cpp:11515]: Invalid contact location for first contact between Empire of Tendor and Grim Souls
[21:30:48][country.cpp:11515]: Invalid contact location for first contact between Belmacosa Autocracy and Grim Souls
[21:30:48][country.cpp:11515]: Invalid contact location for first contact between Holy Roman Empire and Grim Souls
[21:30:48][country.cpp:11515]: Invalid contact location for first contact between Coalition of Rek'Thaa and Grim Souls
[21:30:48][country.cpp:11515]: Invalid contact location for first contact between Lox'Ungrak-Va Democratic Planet-States and Grim Souls
[22:54:15][trigger.cpp:366]: country scope contains invalid object at file: common/scripted_triggers/00_scripted_triggers.txt line: 560
[22:54:15][trigger.cpp:366]: country scope contains invalid object at file: common/diplo_phrases/00_diplo_phrases.txt line: 19130
[22:54:15][trigger.cpp:366]: country scope contains invalid object at file: common/diplo_phrases/00_diplo_phrases.txt line: 19136
[22:54:15][trigger.cpp:366]: country scope contains invalid object at file: common/diplo_phrases/00_diplo_phrases.txt line: 19137
[22:54:15][trigger.cpp:366]: country scope contains invalid object at file: common/diplo_phrases/00_diplo_phrases.txt line: 19145
[22:54:15][trigger.cpp:366]: country scope contains invalid object at file: common/diplo_phrases/00_diplo_phrases.txt line: 19146
[22:54:15][trigger.cpp:366]: country scope contains invalid object at file: common/diplo_phrases/00_diplo_phrases.txt line: 19147
[22:54:15][trigger.cpp:366]: country scope contains invalid object at file: common/diplo_phrases/00_diplo_phrases.txt line: 19154
[22:54:15][trigger.cpp:366]: country scope contains invalid object at file: common/diplo_phrases/00_diplo_phrases.txt line: 19160
[22:54:15][trigger.cpp:366]: country scope contains invalid object at file: common/diplo_phrases/00_diplo_phrases.txt line: 19165
[22:54:15][trigger.cpp:366]: country scope contains invalid object at file: common/diplo_phrases/00_diplo_phrases.txt line: 19171