Hi,

I downloaded backup files from one of our Atlas clusters and attempted to start a local server from these files, however it doesn’t seem to be working… All I get is the following error:

{"t":{"$date":"2025-04-14T15:23:54.996+02:00"},"s":"I",  "c":"CONTROL",  "id":23285,   "ctx":"thread1","msg":"Automatically disabling TLS 1.0, to force-enable TLS 1.0 specify --sslDisabledProtocols 'none'"}
{"t":{"$date":"2025-04-14T15:23:56.969+02:00"},"s":"I",  "c":"CONTROL",  "id":5945603, "ctx":"thread1","msg":"Multi threading initialized"}
{"t":{"$date":"2025-04-14T15:23:56.976+02:00"},"s":"I",  "c":"NETWORK",  "id":4648601, "ctx":"thread1","msg":"Implicit TCP FastOpen unavailable. If TCP FastOpen is required, set at least one of the related parameters","attr":{"relatedParameters":["tcpFastOpenServer","tcpFastOpenClient","tcpFastOpenQueueSize"]}}
{"t":{"$date":"2025-04-14T15:23:56.983+02:00"},"s":"I",  "c":"NETWORK",  "id":4915701, "ctx":"thread1","msg":"Initialized wire specification","attr":{"spec":{"incomingExternalClient":{"minWireVersion":0,"maxWireVersion":25},"incomingInternalClient":{"minWireVersion":0,"maxWireVersion":25},"outgoing":{"minWireVersion":6,"maxWireVersion":25},"isInternalClient":true}}}
{"t":{"$date":"2025-04-14T15:23:57.006+02:00"},"s":"I",  "c":"TENANT_M", "id":7091600, "ctx":"thread1","msg":"Starting TenantMigrationAccessBlockerRegistry"}
{"t":{"$date":"2025-04-14T15:23:57.007+02:00"},"s":"I",  "c":"CONTROL",  "id":4615611, "ctx":"initandlisten","msg":"MongoDB starting","attr":{"pid":7148,"port":27017,"dbPath":"C:/Projects/backup","architecture":"64-bit","host":"DESKTOP-41E8LI3"}}
{"t":{"$date":"2025-04-14T15:23:57.007+02:00"},"s":"I",  "c":"CONTROL",  "id":23398,   "ctx":"initandlisten","msg":"Target operating system minimum version","attr":{"targetMinOS":"Windows 7/Windows Server 2008 R2"}}
{"t":{"$date":"2025-04-14T15:23:57.008+02:00"},"s":"I",  "c":"CONTROL",  "id":23403,   "ctx":"initandlisten","msg":"Build Info","attr":{"buildInfo":{"version":"8.0.6","gitVersion":"80f21521ad4a3dfd5613f5d649d7058c6d46277f","modules":[],"allocator":"tcmalloc-gperf","environment":{"distmod":"windows","distarch":"x86_64","target_arch":"x86_64"}}}}
{"t":{"$date":"2025-04-14T15:23:57.008+02:00"},"s":"I",  "c":"CONTROL",  "id":51765,   "ctx":"initandlisten","msg":"Operating System","attr":{"os":{"name":"Microsoft Windows 10","version":"10.0 (build 22631)"}}}
{"t":{"$date":"2025-04-14T15:23:57.008+02:00"},"s":"I",  "c":"CONTROL",  "id":21951,   "ctx":"initandlisten","msg":"Options set by command line","attr":{"options":{"storage":{"dbPath":"C:\\Projects\\backup"}}}}
{"t":{"$date":"2025-04-14T15:23:57.016+02:00"},"s":"I",  "c":"STORAGE",  "id":22315,   "ctx":"initandlisten","msg":"Opening WiredTiger","attr":{"config":"create,cache_size=7566M,session_max=33000,eviction=(threads_min=4,threads_max=4),config_base=false,statistics=(fast),log=(enabled=true,remove=true,path=journal,compressor=snappy),builtin_extension_config=(zstd=(compression_level=6)),file_manager=(close_idle_time=600,close_scan_interval=10,close_handle_minimum=2000),statistics_log=(wait=0),json_output=(error,message),verbose=[recovery_progress:1,checkpoint_progress:1,compact_progress:1,backup:0,checkpoint:0,compact:0,evict:0,history_store:0,recovery:0,rts:0,salvage:0,tiered:0,timestamp:0,transaction:0,verify:0,log:0],prefetch=(available=true,default=false),"}}
{"t":{"$date":"2025-04-14T15:23:58.229+02:00"},"s":"I",  "c":"WTRECOV",  "id":22430,   "ctx":"initandlisten","msg":"WiredTiger message","attr":{"message":{"ts_sec":1744637038,"ts_usec":227889,"thread":"7148:140720522340176","session_name":"txn-recover","category":"WT_VERB_RECOVERY_PROGRESS","category_id":34,"verbose_level":"DEBUG_1","verbose_level_id":1,"msg":"recovery log replay has successfully finished and ran for 24 milliseconds"}}}
{"t":{"$date":"2025-04-14T15:23:58.229+02:00"},"s":"I",  "c":"WTRECOV",  "id":22430,   "ctx":"initandlisten","msg":"WiredTiger message","attr":{"message":{"ts_sec":1744637038,"ts_usec":228897,"thread":"7148:140720522340176","session_name":"txn-recover","category":"WT_VERB_RECOVERY_PROGRESS","category_id":34,"verbose_level":"DEBUG_1","verbose_level_id":1,"msg":"Set global recovery timestamp: (1744354965, 8)"}}}
{"t":{"$date":"2025-04-14T15:23:58.229+02:00"},"s":"I",  "c":"WTRECOV",  "id":22430,   "ctx":"initandlisten","msg":"WiredTiger message","attr":{"message":{"ts_sec":1744637038,"ts_usec":228897,"thread":"7148:140720522340176","session_name":"txn-recover","category":"WT_VERB_RECOVERY_PROGRESS","category_id":34,"verbose_level":"DEBUG_1","verbose_level_id":1,"msg":"Set global oldest timestamp: (1744354665, 10)"}}}
{"t":{"$date":"2025-04-14T15:23:58.243+02:00"},"s":"I",  "c":"WTRECOV",  "id":22430,   "ctx":"initandlisten","msg":"WiredTiger message","attr":{"message":{"ts_sec":1744637038,"ts_usec":242437,"thread":"7148:140720522340176","session_name":"txn-recover","category":"WT_VERB_RECOVERY_PROGRESS","category_id":34,"verbose_level":"DEBUG_1","verbose_level_id":1,"msg":"recovery rollback to stable has successfully finished and ran for 13 milliseconds"}}}
{"t":{"$date":"2025-04-14T15:23:58.253+02:00"},"s":"I",  "c":"WTCHKPT",  "id":22430,   "ctx":"initandlisten","msg":"WiredTiger message","attr":{"message":{"ts_sec":1744637038,"ts_usec":253265,"thread":"7148:140720522340176","session_name":"WT_SESSION.checkpoint","category":"WT_VERB_CHECKPOINT_PROGRESS","category_id":7,"verbose_level":"DEBUG_1","verbose_level_id":1,"msg":"saving checkpoint snapshot min: 1020, snapshot max: 1020 snapshot count: 0, oldest timestamp: (1744354665, 10) , meta checkpoint timestamp: (1744354965, 8) base write gen: 805608190"}}}
{"t":{"$date":"2025-04-14T15:23:58.268+02:00"},"s":"I",  "c":"WTRECOV",  "id":22430,   "ctx":"initandlisten","msg":"WiredTiger message","attr":{"message":{"ts_sec":1744637038,"ts_usec":268492,"thread":"7148:140720522340176","session_name":"txn-recover","category":"WT_VERB_RECOVERY_PROGRESS","category_id":34,"verbose_level":"DEBUG_1","verbose_level_id":1,"msg":"recovery checkpoint has successfully finished and ran for 26 milliseconds"}}}
{"t":{"$date":"2025-04-14T15:23:58.269+02:00"},"s":"I",  "c":"WTRECOV",  "id":22430,   "ctx":"initandlisten","msg":"WiredTiger message","attr":{"message":{"ts_sec":1744637038,"ts_usec":268492,"thread":"7148:140720522340176","session_name":"txn-recover","category":"WT_VERB_RECOVERY_PROGRESS","category_id":34,"verbose_level":"DEBUG_1","verbose_level_id":1,"msg":"recovery was completed successfully and took 64ms, including 24ms for the log replay, 13ms for the rollback to stable, and 26ms for the checkpoint."}}}
{"t":{"$date":"2025-04-14T15:23:58.274+02:00"},"s":"I",  "c":"STORAGE",  "id":4795906, "ctx":"initandlisten","msg":"WiredTiger opened","attr":{"durationMillis":1257}}
{"t":{"$date":"2025-04-14T15:23:58.274+02:00"},"s":"I",  "c":"RECOVERY", "id":23987,   "ctx":"initandlisten","msg":"WiredTiger recoveryTimestamp","attr":{"recoveryTimestamp":{"$timestamp":{"t":1744354965,"i":8}}}}
{"t":{"$date":"2025-04-14T15:23:58.275+02:00"},"s":"I",  "c":"RECOVERY", "id":5380106, "ctx":"initandlisten","msg":"WiredTiger oldestTimestamp","attr":{"oldestTimestamp":{"$timestamp":{"t":1744354665,"i":10}}}}
{"t":{"$date":"2025-04-14T15:23:58.279+02:00"},"s":"E",  "c":"WT",       "id":22435,   "ctx":"initandlisten","msg":"WiredTiger error message","attr":{"error":-31802,"message":{"ts_sec":1744637038,"ts_usec":278541,"thread":"7148:140720522340176","session_dhandle_name":"file:sizeStorer.wt","session_name":"WT_SESSION.open_cursor","category":"WT_VERB_DEFAULT","category_id":12,"verbose_level":"ERROR","verbose_level_id":-3,"msg":"int __cdecl __win_file_read(struct __wt_file_handle *,struct __wt_session *,__int64,unsigned __int64,void *):288:C:\\Projects\\backup\\sizeStorer.wt: handle-read: ReadFile: failed to read 4096 bytes at offset 32768: Slutet av filen har nåtts.\r\n","error_str":"WT_ERROR: non-specific WiredTiger error","error_code":-31802}}}
{"t":{"$date":"2025-04-14T15:23:58.279+02:00"},"s":"F",  "c":"STORAGE",  "id":50882,   "ctx":"initandlisten","msg":"Failed to open WiredTiger cursor. This may be due to data corruption","attr":{"uri":"table:sizeStorer","config":"","error":{"code":8,"codeName":"UnknownError","errmsg":"-31802: WT_ERROR: non-specific WiredTiger error"},"message":"Please read the documentation for starting MongoDB with --repair here: http://dochub.mongodb.org/core/repair"}}
{"t":{"$date":"2025-04-14T15:23:58.280+02:00"},"s":"F",  "c":"ASSERT",   "id":23091,   "ctx":"initandlisten","msg":"Fatal assertion","attr":{"msgid":50882,"file":"src\\mongo\\db\\storage\\wiredtiger\\wiredtiger_session_cache.cpp","line":123}}
{"t":{"$date":"2025-04-14T15:23:58.280+02:00"},"s":"F",  "c":"ASSERT",   "id":23092,   "ctx":"initandlisten","msg":"\n\n***aborting after fassert() failure\n\n"}

I also attempted to start using --repair, however that also failed, although with a different error dump.

I downloaded snapshots via the built-in backup functionality

Thanks for the taking the time to reply, but we had to access some older data, so even if mongodump would have worked it wouldn’t have helped us, unfortunately.

After doing some additional investigation and testing, it turned out to be data corruption caused by the built-in extraction tool in Windows and also being unable to use a Docker image to run the server with pre-existing data (I’m still not sure why the Docker image didn’t work, though). It all started up fine when re-extracting the data using 7Zip and then running a local version of the MongoDB Community server.