This is the error I get from my tasks which are removig indices. The code works, when its running alone. My working theory is, that the RcConflictSet in the IndexManager instance is the reason for this failure ... but I have no proof for that.

the commitTransaction in line 16 is just after I remove all indices from ONE structure. the removeIndex code is a copy of the createIndex code, so iI think, that all tasks are working on their own (not common) data

ERROR 2261 , a InternalError occurred (error 2261), The object with object ID 1480033747713 is corrupt. Reason: 'CorruptObj, FetchObjId fetch past end' (InternalError)
topaz > exec iferr 1 : where
==> 1 InternalError (AbstractException) >> _signalFromPrimitive: @6 line 15
2 DepListTable >> depListBucketFor: @1 line 1
3 DepListTable >> _add: @3 line 8
4 DepListTable (Object) >> perform:withArguments: @1 line 1
5 LogEntry >> redo @2 line 5
6 RedoLog >> _redoOperationsForEntries: @6 line 4
7 DepListTable (Object) >> _abortAndReplay: @15 line 20
8 DepListTable >> _resolveRcConflictsWith: @3 line 10
9 System class >> _resolveRcConflicts @21 line 26
10 System class >> _resolveRcConflictsForCommit: @4 line 8
11 [] in System class >> _localCommit: @28 line 42
12 ExecBlock0 (ExecBlock) >> onException:do: @2 line 66
13 System class >> _localCommit: @16 line 44
14 SessionMethodTransactionBoundaryPolicy (TransactionBoundaryDefaultPolicy) >> commit: @3 line 3
15 System class >> _commit: @8 line 16
16 System class >> commitTransaction @5 line 7
17 [] in WCATIServiceClass class >> removeAllIndices:total: @59 line 28
18 SortedCollection (Collection) >> do: @6 line 10
19 WCATIServiceClass class >> removeAllIndices:total: @35 line 24
20 Executed Code @2 line 1
21 GsNMethod class >> _gsReturnToC @1 line 1
topaz 1> commit
ERROR 2249 , a TransactionError occurred (error 2249), Further commits have been disabled for this session because: 'CorruptObj, FetchObjId fetch past end'. This session must logout. (TransactionError)
topaz > exec iferr 1 : where
==> 1 TransactionError (AbstractException) >> _signalFromPrimitive: @6 line 15
2 System class >> _primitiveCommit: @1 line 1
3 [] in System class >> _localCommit: @21 line 30
4 ExecBlock0 (ExecBlock) >> onException:do: @2 line 66
5 System class >> _localCommit: @9 line 31
6 SessionMethodTransactionBoundaryPolicy (TransactionBoundaryDefaultPolicy) >> commit: @3 line 3
7 System class >> _commit: @8 line 16
8 System class >> _gciCommit @5 line 5
9 GsNMethod class >> _gsReturnToC @1 line 1
topaz 1> doit