Project chios raised exception class 'External: SIGSEGV'. lazarus / 12-Debugger ---------------------------------------------------------------------- orionyx · 2018-09-24 21:10 I am trying to run Lazarus under Ubuntu 18.04 on a laptop with 8gb and a 200Mb partition on a 500Mb hard drive shared with Win7. I am writing a database application using MySQL. The database has 11 tables, 4 of which have some data present already. I am trying to view and edit this data using a TDBEdit component with a TDBNavigator, with a TDBMySQL57Connection, a TSQLQuery, a TDataset and a TTransaction, all properly connected. The SQL statement in the TSQLQuery is "select * from Garments". When I show the form with this stuff on it, the 23 records in Garments appear in the TDBGrid. Excellent! If I click on the grid, or use the arrows to move the cursor on the TDBNavigator, the program gives me this error: Project chios raised exception class 'External: SIGSEGV'. The Assembler window opens up with this in it: 0000000000790BFE 0000                     add    %al,(%rax) DB$_$TDATASET_$__$$_CHECKACTIVE 0000000000790C00 488d6424f8               lea    -0x8(%rsp),%rsp 0000000000790C05 4889f8                   mov    %rdi,%rax 0000000000790C08 4889c7                   mov    %rax,%rdi 0000000000790C0B e8101b0000               callq  0x792720 0000000000790C10 84c0                     test   %al,%al The bold text is the line at which the error occurs. I run the program without debugging: same thing. I run the program outside the IDE, and instead of the error message, the forms just silently disappear leaving no trace. I have looked up this error in this forum, and so far the most useful suggestion from 2009 is - go for .net or java. I don't like either, but I do know they work. So, what to do? ---------------------------------------------------------------------- HeavyUser · 2018-09-24 21:13 looks like you are trying  to access an uninitialized variable. ---------------------------------------------------------------------- orionyx · 2018-09-24 21:22 Thanks for the suggestion. I've looked for that, and it's not the answer. The error line mentions a TDATASET and seems to be querying its ACTIVE flag, but the TDataset on the form does not have an Active property - it's called Enabled. I tried initializing the Active, Enabled and Connected properties of my components to False and then setting them to True when the form starts - the problem remains. Older answers on this forum seem to indicate that this is a sporadic problem with no definitive solution. ---------------------------------------------------------------------- HeavyUser · 2018-09-24 21:32 Active is a public property of the TDataset and all its descentants have it. If yours does not then I have to ask for the components you use. PS   Keep  in mind public properties are not shown in the object inspector. ---------------------------------------------------------------------- orionyx · 2018-09-25 07:59 Solved! I went into the MySql table definition and set an autoincrement field as the primary key. Now it works perfectly. But it took a lot of reading through lots of tangled documentation to get there. Thanks for your interest and suggestions.