I am copying directly from the log, not removing anything (just saying because it’s weird):
[start] 08:10:26 INFO: Automatic upgrade is always enabled for candidate releases.
[start] 08:10:26 WARNING: Error opening database: sync C:\Users\Skill Lan House\AppData\Local\Syncthing\index-v0.14.0.db\MANIFEST-000000: Espaço insuficiente no disco. (is another instance of Syncthing running?)
[start] 08:10:27 INFO: syncthing v1.10.0-rc.3 "Fermium Flea" (go1.15.2 windows-amd64) teamcity@build.syncthing.net 2020-09-15 17:38:23 UTC
[start] 08:10:27 INFO: Automatic upgrade is always enabled for candidate releases.
[VYQYH] 08:10:28 INFO: My ID: VYQYHHG-X7J7BD2-GW5WCIW-V5KLFQ2-QEZPIQ2-3MPGZ3Z-XMCZUKK-WXARAQF
[VYQYH] 08:10:29 INFO: Single thread SHA256 performance is 490 MB/s using minio/sha256-simd (428 MB/s using crypto/sha256).
[VYQYH] 08:10:29 INFO: Hashing performance is 409.83 MB/s
[VYQYH] 08:10:29 INFO: Migrating database to schema version 1...
[VYQYH] 08:10:29 INFO: Migrating database to schema version 2...
...
Somehow on first opening it gets a insufficient space error, then directly after restarting it doesn’t any more. A minute later the insufficient disk space error pops up again.
Looks like there’s something wrong with your filesystem. It sometimes reports it is full. No idea why, but that’s a system level error, not one from Syncthing. Before continuing to look into why the db grows so much, the filesystem must “become sanely behaved again”.