[SERVER-55313] Unable to start standalone mongod after downgrade from 4.4 -> 4.2 -> 4.0 Created: 18/Mar/21 Updated: 08/Mar/22 Resolved: 24/Mar/21 |
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| Status: | Closed |
| Project: | Core Server |
| Component/s: | Upgrade/Downgrade |
| Affects Version/s: | None |
| Fix Version/s: | None |
| Type: | Bug | Priority: | Major - P3 |
| Reporter: | Cayden Dagnall | Assignee: | Eric Sedor |
| Resolution: | Done | Votes: | 0 |
| Labels: | None | ||
| Remaining Estimate: | Not Specified | ||
| Time Spent: | Not Specified | ||
| Original Estimate: | Not Specified | ||
| Environment: |
RHEL 8 |
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| Operating System: | ALL | |||||||||||||||
| Steps To Reproduce: |
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| Participants: | ||||||||||||||||
| Case: | (copied to CRM) |
| Description |
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When attempting to down a standalone mongod from 4.4 -> 4.2 -> 4.0, the 4.0 mongod fails to start. Our specific use case is upgrade from 3.6 -> 4.4 and then downgrade from 4.4 -> 3.6, but this error also happens without upgrading an existing database and simple starting from 4.4. Downgrade from 4.2 -> 4.0 works when starting at 4.2. Downgrade also works when performing a mongodump/mongorestore between 4.2 -> 4.0 when starting from 4.4.
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| Comments |
| Comment by Eric Sedor [ 24/Mar/21 ] |
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Thanks cayden.dagnall@leidos.com. In reviewing the documentation I've requested some clarifications in I'll close this ticket now. Be well! |
| Comment by Cayden Dagnall [ 18/Mar/21 ] |
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Thanks, I missed that in the documentation. |
| Comment by Daniel Gottlieb (Inactive) [ 18/Mar/21 ] |
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Once a MongoDB 4.4 binary starts up on data files, those data files can never be used by a MongoDB version 4.2.5 or earlier. If you need to go from MongoDB 4.2.6+ to an earlier version, you'll have to perform an initial sync (for replica sets) or a mongodump + mongorestore (for standalones) into a 4.2 binary on a fresh dbpath. Then continuing your downgrade procedure should work. See the documentation on the downgrade floor here. |
| Comment by Cayden Dagnall [ 18/Mar/21 ] |
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Versions reproduced on: 4.4.1 4.2.12/4.2.13-rc2 4.0.22/4.0.23 |